Walking is wonderful! Don't feel like it's a waste of time, it's not as if your body refuses to burn calories if you're not running 6mph
Plus with time you'll be able to work up to walking for longer periods of time, faster, longer distances, etc., if that's what you choose. I started out walking outside, and it was a struggle to do a mile in twenty minutes, but now a year later I've worked up to doing a half-marathon, I can do a mile in about fourteen minutes, and I've just started working on running a bit. So keep with it!