Took my first steps yesterday

Wow!  I took my first steps yesterday with my leg.  It was so weird and scary.  You all know that I've been in my chair since May.  I only had it on for about 10 minutes and I couldn't believe how winded I got just taking a few steps out my front door then back to my chair.  My back started hurting immedicately, too.  Anyone out there have back pain when they first walked?