They may also have different goals. Some people simply want to shed a few pounds while others want to tone flabby muscle. Others want to gain mass or become better at a certain sport. Though the motivations and goals of people may be different, the pathway in between is always the same. That pathway is exercise.
Your motivation is not important to make progress but different goals require slightly different pathways. Those who want to lose weight must have an exercise plan different from those who want to gain mass or get stronger.
To lose weight or reduce flab, you must start doing lightweight exercises and cardio. Lightweight exercises include lifting light weights many times and some simple body weight exercises (push-ups, sit-ups, pull-ups, etc). Cardio includes exercises that work your lungs and heart by inducing heavy breathing. These include running, swimming, and most competitive sports (soccer, football, basketball, etc). To do lightweight exercise a person should choose a weight that they can lift at least twenty-five times in a row. To get maximum results, you should rest a couple minutes after doing the first twenty-five repetitions and do twenty-five more. Repeat that and do twenty-five repetitions for a third time. This method is called sets. Doing twenty-five repetitions at a time with one weight may tire you out, but after a couple minutes, you should have gained enough strength to repeat the exercise (each set will be tougher to do but you should be able to manage). This ensures that you get the most out of your muscles, getting fast results.
For cardio, you have many options to choose from. Running or jogging is the simplest exercise and produces good results. However, swimming is much more efficient than jogging. Swimming ten laps is equal to about an hour of jogging. It'll save an incredible amount of time and does much more for your body. For instance, swimming has a better effect for your lungs as the exercise makes you conserve your breath and use it over a long period of time. Swimming is also a full-body exercise, exercising EVERY SINGLE part of your body. This is due to the water, which acts as a resistance, impeding movement in every direction. Swimming (along with other sports) also helps increase motor function as they do not use the same movement over and over again, a defect of running.
For those wishing to bulk up or gain muscle mass, they must take a slightly different approach. Cardio has nearly no use in short term muscle building so it can be disregarded. Lightweight training also has little use but the opposite, heavyweight training is exactly what we will be discussing. Heavyweight training involves picking a very heavy weight that you can only lift 4 to 10 times. You must also use the set method to get maximum results. However, nutrition has quite a bigger role in heavyweight training. You must consume much protein rich food and protein supplements if you want maximum results.
Exercise much, rest much, and always gain knowledge about how to best exercise your body. Try different movements to test your muscles from different angles and switch between free weights, body weight, cables, and machines. Have fun exercising and reach your goal!