How much exercise is too much when TTC?

Hey guys, so I've been wondering about this every cycle I've been TTC (3 months now) and thought I'd solicit your expertise. I am 29, healthy BMI, no health problems, but I am NOT an athletic person. Used to do a fair amount of yoga, but now the most exercise I typically get is a 10 minute walk to and from the train. I know this is not great, and I'm trying to make better habits. But I don't want to push myself too hard while I'm TTC and risk miscarrying. What do you suggest? And say if I'm in the early early stages of pregnancy (🤞) and I were to go running or something, would I fuck it up?