Activities are severely lacking. Strip club and shops don't work properly, hell you can't even earn money....
HOWEVER, that said, I have a habit of when I first spawn into the game in my apartment at 06:00 I simulate waking up, drink green juice, get on my Yamaha r6 and go down to Vespucci Beach and go for a jog and workout. Then go home, shower, then I'll go to the PD and go on duty for 08:00.
After my patrol I'll go off duty at the station then head home, have a beer and then get into bed and that's when I log off.
(And yes you can do yoga through Model Spawning -> Animation Menu) 😉