I feel that you should start your day with a brisk jog on a treadmill or in your neighbourhood. If you are doing it outside, you will get plenty of fresh air. Later, use a yoga mat and do some necessary exercises like planks, side planks, side crunches, bicycle crunches, vertical leg crunches, sit-ups and more. Each of the exercises must be done in three sets of 15 to 20 reps. The entire workout should actually be done in an hour or two. The more you exercise, the more you stay fit. Some exercises will actually help you more than others. Swimming, cross-fit training and cycling are some benevolent examples.