Do I need to join a gym in order to gain the benefits of regular exercise?

You do not have to join a gym to gain the benefits of regular exercise. A gym is helpful for people who do not know what to do, need motivation and need social support but even then there are other ways to get those things outside of the gym. For example, if you don't know what kinds of exercise to do start by thinking about the 'active' things you already love doing, search the internet for an exercise plan or bring a personal trainer to your home for one or two times so they can provide you with an at home exercise routine. There are also ways outside of the gym of getting and staying motivated. Involve your spouse in an activity that you both like and you are not only helping to motivate each other but you are providing social support for each other. You could join a group of people who enjoy similar activities (i.e. walking, running, cycling). Groups not only help with motivation and provide social support but it provides people in the group with a sense of accountability, belonging, and cohesion. 

You can obtain the benefits of regular exercise without joining a gym by remaining active on your own terms. For individuals, a gym membership affords the opportunity to create a social experience out of working out, thereby enhancing motivation to keeping a healthy and fit lifestyle.  A gym also provides access to what would otherwise be considered somewhat unreasonably expensive exercise equipment. Gyms also typically employ personal fitness trainers who can provide you with additional education or accountability if this is something you need. If you have the motivation to workout independently, and a basic understanding of what it takes to be physically active, you can easily obtain similar results without the added expense of a gym membership.

In order to obtain the benefits of regular exercise, your primary activities should involve cardiorespiratory and resistance training.  Any activity that places demand on both the cardiovascular and respiratory systems for an extended period of time will fulfill your requirements of this type of training (30 minutes is ideal).  You can accomplish this on your own through activities such as running, biking, and hiking.  However, it is suggested that you engage in activities that you enjoy, so do not exclude options such as roller blading, swimming, or others.

The benefits of resistance training include increased lean body mass (muscle tissue), reduced body fat, increased strength and bone density, to name a few.  Typically resistance training is thought of in terms of exercise equipment, however you can still gain benefits by incorporating body weight exercises such as push ups, lunges, and squats.  You also can look into purchasing inexpensive equipment to use at home such as stability balls, resistance tubing, and hand weights.  By purchasing these types of equipment, you will expand your options at a lower cost and incorporate change and creativity in your workouts.