The main problems were originally:

If you only do strength training, you end up being more likely to stay up late.
Because cardio machines like stair climbers are always too boring and repetitive, making it hard to stick with it.
Things changed after I started playing tennis regularly:
There are challenges that gradually improve your technical understanding, a sense of accomplishment, and social interaction along with it.
It also fills up all the time slots in the aerobic Zone 1~5,
so at night it’s easier to sleep and I stay up less.