For me, exercise and sleep definitely. I exercise for 60-90 minutes each day, usually in the gym although some people find that boring and prefer outdoors stuff. But whatever sort of exercise it is, you should definitely take some regularly, every day if possible. When I broke my foot a couple of years ago and couldn't exercise, I was back onn anti-depressants within 10 days, so I know how much of an impact it can have on mood. And good sleep is hugely important for me too.
DX: Bipolar Type 1 with psychotic features
Meds: Quetiapine 800mg, Fluoxetine 60mg, Zopiclone/Diazepam as required
"Stop the world....I want to get on"