Does this sound like appropriate exercise?

...For someone who has only just began exercising daily. Although I walk on and off a lot I've decided to do it everyday. So the minimum that I am to do each day is 20 minutes of walking up hill where I walk up the steepest hills in my suburb at the quickest pace I can and then I walk back around to the otherside of my suburb which takes me around about another 40 minutes. If I do this everyday is it good enough walking up those hills makes my pulse go pretty hard, or should I do more?