How much walking is safe?

I was feeling good at week 11 day 4 and tried to be a smart Alec, went for a walk in the park. About 2.2km then I had red bleeding(that is like real red and filled up probably 1 panty liner) in the evening. So I immediately had my progestrone insert and thank God the bleeding subsided. Went in to see my doc the next day, thank god all is good. Doctor didn't say much about the cause of bleeding and advice for me to avoid sex for the moment. Now I am really scare of going on a walk again. Any advice from mum to be out there? How else do u all exercise in the safe way?