Begin with something small; establish a fixed time for it every day. Practitioners who have time can perform it at any hour, almost. For those with many commitments and a tight schedule, the best times are early in the morning or before going to sleep. Parents need to juggle things in order to make room for regular training times, sometimes mornings and evenings are dedicated to the children. Finding time is difficult, but possible.
Make your newly developing habit something very small and easy. This is the sapling of the tree, and must not be taken lightly. It is surprising how many tries this may take, your habit might grow and fade more than a few times. It is surprising how difficult it is to perform only a single sit-up each and every morning. This is the inertia of our old ways. But actual doing, actual persistent work, will change you in more ways than one.
You can begin with a single push-up or just by putting on running shoes, walking a few minutes, running for one minute and then taking the shoes off, no more. You can begin with one strike, one block and one kick, no more than 20 seconds for all exercises. This is your base camp which must be performed religiously every day at the same time, except for one regular day in which you take a rest from training. After several weeks or months we have a physical habit, an independent training kernel has been created. Upon this habit we can, over the years, gradually build a couple of hours' training every day, even without the presence of a group or an instructor.
By using patience and the knowledge of slow and steady growth, we create an independent and fixed training kernel.