What gets in the way of exercise?

Anything can get in the way of exercise. Obstacles come in the form of reality: sick kids, extended work hours, illness; or come in the form of perceived obstacles: lack of a gym facility, lack of transportation, lack of money, vacations, lack of energy, family, friends and work. Both are "real" but some perceived obstacles are mental blocks that can be overcome with awareness.

Great answer above, the thing that generally gets in the way is the person.

There are exceptions when life really makes it impossible but almost always people can find time or resources.  Most people will use excuses as a means of justifying not exercising.  

When you get started and in the middle of a routine almost all of us know how great you can feel but getting started is usually the hardest part.  It is why stopping should never be an option.  Back down a little, reduce time but never quit because once you quit you can justify any reason for not going back.  

Having a great support system or trainer is also very important.  If people or groups are invested you they will hold you accountable and the chances of making excuses and quitting decreases. 

There are many things that get in the way of exercise. Time is one of the biggest reasons people don't exercise. Incorporating exercise into someone's day can help with this. The second is not having the proper social support to exercise. Most people who are new to exercise enjoy exercise when it's with someone else; a friend or family member. That provides companionship and accountability. The third reason is lack of options. In starting an exercise program it can be challenging to know where to begin and to have knowledge of what all the options are. All of this can be very confusing and actually lend itself to someone not starting because they feel overwhelming.

Some other reasons include: lack of knowledge, it's uncomfortable, lack of facilities or equipment, and cost.