'Course everyone's different. If you're nervous about the effect, you could always do an Epsom Salts bath before bed and that will draw out any lactic acid caused by muscle exertion. You could squeeze lemon into some of your water througout the day to help equalize the acids produced by the muscles.
I try to walk/hike everyday. I like to go about 3-5 miles up and downhill. I couldn't do that in the beginning, though. Just walking around the block would give me panic attacks and I wasn't agorophobic at all! So you're doing pretty good there, girl! YAY!