Won't slow it down. The general advice to do what you would normally do. If you never exercise and you suddenly decided to run 10 miles a night, you can make yourself quite ill as you're not having the calories to do it. However, if you've always been very active, it shouldn't be too bad.
If you've not exercised before, then increasing the walking you're doing and some nice exercise classes like pilates can help with toning. You certain;y don't want to overdo it and stress your body.
I;ve always run and done endurance riding, and I've done it throughout SS with LL with no ill effect.