What if you didn't really exercise much before pregnancy?

I had been away from a regular workout schedule for over a year but had been meaning to get back into a routine before getting pregnant. I got pregnant sooner than I thought possible and here I am at 6 weeks! I'm constantly reading that if you were working out before becoming pregnant it is safe to continue doing so while you're pregnant. But what about someone like me who was not very active before pregnancy but wants to start now? What kinds of exercises are safe to do for someone in my position?