Most changes were ones my body dictated. I didn't want to drink or smoke (I would have stopped smoking regardless and cut down on drinking, but my body had already said "no thanks")
When i was at the stage you're at, OP, I was still doing everything as normal, I was just as active and eating normal foods (except I cut out soft cheeses like brie and deli meats without heating first, and was cautious about sushi). Then my symtoms kicked in and I had to alter my diet to things that didn't make me too sick, i was too tired to do anything at all let alone go for a run (I went for my last run at about 6.5 weeks). I also got an aversion to coffee so that was out too. I switched to tea, which i could stomach.
Lots of people manage to keep going business as usual, but lots also find the first trimester very debilitating, and it can kick in at any time, so don't beat yourself up if next week you absolutely cannot get out of bed and only want to eat hot chips.