I find breaking the momentum (good or bad) is the hard part.

Since last year I adopted a "work all week, play all weekend" strategy; I basically work my 8 to 4, then immediately start working around the house, in projects, in hobbies, anything. I set myself a 7 pm warning to start wrapping up so I don't leave a mess behind, shower and chill until it's time for bed.

On weekends it's all fun stuff unless we need to do some special project around the house that could not be done during the week (usually some gardening stuff).

On the exercise front, I run 3 to 5 KM 3 times a week and literally play with some dumbbells also 3 times a week (usually during boring "listen only" meetings)

I have never accomplished more and felt progress than before. Now that the rhythm is going, I get restless if I can't do stuff (say due to weather or other commitments). Just yesterday my wife told me not to do as planned because we are undergoing a heat wave and it was "horrible" outside, yet I couldn't contain myself and decided to do what I could... I ended up completing the task of removing an old shurb we wanted to get rid of and I slept great with a sense of accomplishment and a bit of "good pain" from all the exercise