Creating a well-formed fitness program is like writing a thesis. It begins with a general question: What do you want to do with your body?
Your answer is your conclusion. The body of your work is what it will take to get you there. Your starting point is your fitness level right now.
Your fitness program needs to offer realistic goals based on your current fitness level. For example, if your end goal is to play a complete tennis match comfortably, you must first evaluate the state of your current body. Be honest with yourself, yet give yourself grace. Do you have a difficult time balancing on one foot? Do you get winded easily? Do you have a lot of weight to lose?
If you've answered "yes" to any of these questions, then simply picking up your racket is, surprisingly, not your starting point. Tennis is a sport that requires specific conditioning. If you're getting back into shape, jumping headlong into a specific sport increases your risk of injury and will likely decrease your enjoyment of the sport. If you're injured or you lose motivation, you're less likely to reach your goal. You deserve to reach your goal!
So let's rethink the concept of your starting point. If a full game of tennis is your goal, your starting point is off the court. Begin with mastering the basics of balance and coordination. Stand on one foot. Then use the wobble board. Then use the BOSU ball. Build up your cardio strength on the treadmill, elliptical, or bike. Or go for a brisk walk until you can run. Then run until you can trail run. Begin lifting weights to increase the strength in your tendons and muscles. Then increase the weight. Run some more. As your body weight decreases, your cardiovascular capacity increases, and your speed quickens, throw a medicine ball up in the air or against a wall. Jump on and off of plyo boxes. Run sprints.
Only then, after your ankles, calves, thighs, hamstrings, hip flexors, abdominals, back, and arms have all made thousands of new connections with your brain on how to run fast, jump, slide, and hit without falling, pulling a muscle, twisting an ankle, blowing out your elbow or passing out, you will have reached your final goal of becoming fit enough to play a full tennis match. Only then should you pick up your racket and step onto the court.
Playing sports are a great way to stay in shape. They are not an effective weight-loss plan, however, because of the risk of injury. People who wish to play sports should be relatively conditioned before they begin. If you've decided that you want to play soccer, tennis, basketball, baseball, slow-pitch softball, water polo, or run wind sprints, take some time to get your body ready. Begin with a general plan to get your heart and muscles strong. Then get specific. You should incorporate exercises into your fitness program that will help you reach your goal safely and enjoyably only after you've conditioned your body to meet the increased demands.
So the question is: What do you want to do with your body?