WOW am I out of shape

So I know people say you shouldn't work out until 6 weeks after childbirth but my doctor totally didn't tell me that :) So I've been going to the gym sporadically and halfheartedly working out on the elliptical etc...Today I decided to try running for the first time and I can hardly believe that I once ran for 2 hours without stopping!!! 20 minutes and 1.8 miles and I was about ready to collapse (but totally in a good way). I guess it's gonna take awhile before I can start running marathons huh? I'm TOTALLY up for the challenge!!! (I hope)