My top tips for adherence and fitness longevity (for life indeed!):
1. Find your passion(s),
and do them. Avoid doing STUFF you don't really respond to, or that simply doesn't light your fire
2. Decide on the minimum amount of sessions you're prepared to do each week
(but make this realistic) then do that without fail.
3. On short breaks, drop it all and rest!
(although I do like to keep a bit of Yoga going as it's tough to rebuild flexibility if you lose it). Train to live don't live to train. Your body rebuilds with rest. (I have total addicts who don't get that and wonder why I'm as fit as them or fitter even though they do way more and they WON'T be told as they are addicted!
4. Find your personal drivers for doing fitness.
If you do it because you think you SHOULD (prescribed) you're in trouble!
5. Find your style (and ideal environment).
If you're happiest on your own running up a mountain, that's fine.
If you need the company of others go to group sessions. If you hate (say) men;s weights areas find a female boutique gym, if you want the best and can afford it - get 1-2-1 training ... etc
6. If you find a great trainer - stick with them. We don't appreciate flighty floaters!
7. Late entry! (Yet I'm always saying this):
Work across the board in as many planes of movement as possible.
Here endeth todays sermon etc!