What preparations can I make to increase my chances of fitness success?

To increase your chances of success, set some goals and track the outcomes of those goals. Also, be prepared to celebrate the accomplishment of each goal. This can help you stay motivated. It often helps to write down your goals on a sheet of paper. As you write, think about setting goals that are specific, challenging, measurable, action-oriented, inspirational, and timely. A specific goal is one that is clearly defined with a definite destination. You are more likely to achieve a specific goal such as "lose five pounds" than simply setting out to "lose some weight". Choose goals that challenge you rather than those you can achieve easily. For example, if it is easy for you to spend 30 minute a day on the treadmill, then make it your goal to spend 45 minutes a day at 50% speed on the treadmill. This goal is also action-oriented rather than allowing you to achieve the goal without any hard work. Setting goals that are action-oriented will help give you something to look forward to once the goal is attained. In addition, you should set goals that can have their progress measured from week to week and are achievable within a short period of time to ensure that you stay determined. Finally, goals should be inspirational to you and in line with your ideals to help you stay motivated and focused on the big picture. Planning your journey ahead will give you greater motivation and enthusiasm for your exercise program.

To increase your chances of fitness success, it often helps to eliminate or reduce the common barriers that can hinder your success. For example, eating too much junk food is easy if it is readily available in your house - so throw out the empty-calorie foods now and eliminate that temptation to overeat in the future. If you work out at a gym, keep an extra set of workout clothes in your car so you can always go straight to the gym even if you forget your normal workout clothes. Establish a reserved block of time for yourself on your training days - and let others know about it! It will help keep you accountable to your training schedule and others will know not to bother you during that time. Plan tangible rewards for the smaller successes and truly reward yourself when you reach those goals! Treat those rewards as an integral part of your training success - and not just as "time off"!
 Most importantly, prepare for setbacks! When you understand that setbacks will happen, and know that they are a part of everyone's path to success, you'll be able to get back on track without letting a setback become an "all-or-nothing" road block. Consider each setback as an addition to your training to make you that much stronger - like adding more weight to your weight workout or increasing the incline to your running workout. Incorporating setbacks into your training schedule will help your chances of fitness success by using them to improve you rather than stop you.
 

Great answers, in addition I think the first step is to have a support group or hire a fitness professional.

The above statements are true and wise but the truth is most people who do it by themselves stop.  People have a much better chance to succeed if they have accountability.  A support group or a fitness professional will help keep the emotions and feelings out of fitness and keep you focused on the truth.  

A group or coach will help hold you accountable to the above and encourage you to persevere and continue.  Setbacks are a part of it, bad food and time is a part of it and you have to take the advice given but whenever you do it in a group or accountable to someone your chances of success improve dramatically. 

There are many ways to insure fitness success over the long term.  Nutrition is a good start.  I find that I feel better and more energetic if I'm not bogged down by a lot of chemical-laden "food", sugar, and empty calories. This makes exercise much more enjoyable.  Schedule your workout into your day--write it on your planner in ink.  Post visual cues where you will see them regularly (hang your skinny jeans on the closet door,  tape an old photo of how you don't want to look anymore on the bathroom mirror--you get the idea).  Bombard your inbox with free newsletters from fitness, health and light cooking magazines to remind you that fitness is a priority in your life.  "Like" or "Follow" celebrity trainers on Facebook or Twitter.  Most importantly, monitor your progress and notice the changes in your body as you get more fit.  Have short term and long term goals in mind and reward yourself for the little successes along the way.  There's nothing like a little positive reinforcement to keep you goin'!

There are several strategies to have in place to help make getting and staying fit possible. First, set realistic goals, write them down and look at them regularly. Second, schedule your workouts in your calendar. Finally, get support. Family, Friends, or professional support with a trainer will help you to succeed.

Have a consultation with your doctor to make sure you are ready for a fitness program to avoid any potential physical set-backs.

Set attainable and realistic goals and put a date on it.

Have a plan in place to achieve these goals.

Find an accountability partner or tell everyone you know what your goals are, this will keep you on your accountability track.

Celebrate your successes!

I echo the previous suggestions.  It is very important to set goals, understand you will have set backs and need to pick up and continue on, replace unhealthy snacks with healthier snacks, and be accountable to someone.   Lifestyle changes take effort and commitment, and living healthy is a daily choice, but you are so worth it!!

Create an environment to prevent from making poor food choices.   Some people are able to go through their house and replace all the unhealthy food with healthy choices and some cannot.  You may have a better chance at long-term success if you target one food at a time then move to another.  For example, I do not buy ice cream or chips that sit in the house because if they did, I’d eat them.  I only buy single servings of ice cream once a week so I eat it, it is a reasonable portion size, and it is gone.  If I want chips, I buy a single serving (usually baked).  Once I got use to not having chips in the house I switched to whole wheat pasta.  No vegetable oil, only olive oil or Pam.  I changed things one at a time until my environment supported a healthy lifestyle.

Accountability is an important aspect.  Simply knowing there is that person who is going to ask about your eating can be enough to support making a healthier choice.  Having the reinforcement of healthy choices also helps tremendously because that advice will run through your mind as you stand in the ice cream isle contemplating which flavor to purchase.

1.  Make your workout a priority by scheduling time on your calendar.  It gives you a visual reminder and defines when your workout will be happening each day of the week.  This helps hold you more accountable.

2. Share your goals with someone, a friend, a workout partner, a personal trainer, or a spouse.

3. Write down what you are eating, why you are eating(hunger, boredom, sadness, happiness) and how much you are eating.  It is hard to change your habits if you don't know what they are.  Journaling your food helps you to determine the changes that will make you more successful. 

4.  Make sure your workouts are progressive.  If you want your body to change your workouts have to change.  The body adapts to the stimulus' it is subjected to. If that stimulus is not greater than it dealt with before it has no reason to get stronger, faster, or more efficient.  Progressions can be applied to your workout through changing duration, intensity, repetitions, sets, exercises, or recovery time.

To sum it up there are three basic bases to cover...nutrition journaling, implementing a progressive cardio and resistance training plan, and remaining accountable!

The key to motivation is a sense of control over what you are doing, when you are doing it and where. Choose something you know you'll love or something you think you'll grow to love and have fun with.  Add in social support such as friends, co-workers or family members to keep you engaged in the activities.  Similar to anything new, you need to realize that you are starting off with a sense of newness and possible discomfort, but those feelings go away; as with anything in life that is new. 

Set goals is using SMART goals. Goals should be specific, measurable, attainable, realistic and time based. In setting goals it's important to think realistically (doing some exercise but not too much exercise) about setting 2-3 small, short term goals that come out of your long term goals: losing weight and the ability to be active with my family. Those goals should include intent (intending to go to the gym) and effort (I was able to climb one or two more stairs). As you find yourself reaching one goal you'll find your confidence increasing to reach the next goal. You will also need to take into consideration what 'things' help you to exercise: groups, friends and family and what 'things' get in the way of exercising: time, energy, work and motivation. Once you are aware of what things you need to exercise and what gets in the way you are better able to incorporate those into your goals to help you move forward and build confidence. For example, if you don't like to workout alone then it's important to be aware of that, add that to your goals and find someone to workout with you. If work is a barrier to exercise, add that to your goals and find a way to either incorporate exercise into your work or add it before or after your work. 

First see a doctor and have a check up.  Then see if you can get a free consultation with a dietician.  then look for a local gym that has a training staff that is available when you can train.

Start with identifying the motivation behind your desire to be fit. Clean your kitchen out of foods that are high in calories and low in nutrients. Tell your family and friends what you are up to and ask them to join you so that you can support each other. Commit to a specific time or times a day you will workout and find ways to get up and move when you are not working out.