The way is this. The (optional?) activities one likes can be sandwiched between essential activities in CPM. For example, an exercise activity (like walking to fetch groceries) can precede an essential activity like preparing or eating a meal. So that if one doesn't walk, one doesn't eat!
A very busy surgeon would play a vigorous game of squash after duty, before going home. So if he doesn't play, he can't go home!
If a person is fond of practising music, he/she should arrange their schedule, so that they can't leave for work without their morning riyaz. There is an apocryphal story of the legendary teacher Ustad Allauddin Khan denying food to his disciples unless they practiced enough!
Similarly with reading/writing. The ubiquitous Sudha Murthy had a creative urge to write, but no free time in her hectic day. So she decided just to get up an hour earlier so that she wrote before her day began. Similarly an avid reader can pledge to go to bed only after reading at least 100 pages!
The trick is to internalise activities of interest into one's daily inescapable routine so that one cannot pass a day without doing them.
Of course, it cannot be emphasized enough that this internalising interest into routine is possible only if one has EXCEPTIONAL FOCUS & MENTAL DISCIPLINE.
