Hello!
I'm afraid to get Hill fit, you really need to get walking up hills. Easiest way is to go to the menu at the top of this page and look at the hills nearest you. If you've got an hour or two free try a sub 2000 then just move up to bigger stuff as you fitness grows. This is great for honing your navigational skills too. A there's no point in getting fit if you don't know where your going, lol
Enjoy! Hill are great for your mind and fitness