Walking around is one of the simplest ways to work out, and it's helpful for both your mental and physical health. I would suggest walking shoes, however, if your terrain isn't very soft.
Mostly I just pace around the house. It seems to help me work through my thoughts.
For how long have you been sleepwalking? It's more common in kids than in adults, and usually outgrown in the teen years.
It's hard to say, because I still wake up in my bed. But sometimes the door will be open when I know I closed it.
That's good that you'll usually wake in bed. However, you should make sure that your surroundings are safe for it--no open windows, or unlocked doors that lead to stairs, or obstacles that you may fall over. 
I've never had an accident, so I guess I must be pretty aware of my surroundings.
Sleepwalking may be relatively harmless, if obstacles are not an issue, but it is best to make sure that it is not caused by a related sleep issue. Something like sleep apnea or narcolepsy may be an underlying condition which triggers it.
I'm not narcoleptic. I don't fall asleep unless I mean to.
While you should still consult your doctor, medical treatment is really only necessary when there is the risk of injury or those underlying issues. So, you may find that you need not make any changes.
I can't afford a doctor. I'm too poor.