Is it an easy task getting back into shape and losing stretchmarks after giving birth?

I'm worried about my body how it will look after I'm finish having the baby. I know vanity shouldn't be my top priority, but I want to know if there's a simple and easy way to lose stretch marks on the hips, belly, and thighs and getting back into shape after. I know losing weight and stretchmarks won't be instantaneous but I want to find a way to get rid of them no matter what and however long it may take. I hear many women stay a little "bigger" after having a child and I don't want to stay that way(then again, it's probably because they didn't work out or anything after). I do apply the Palmers stretch mark lotion very often at the moment, but other then that, I have no idea what to do. My due date was June 4, 2010 but the baby hasn't come out yet. Should I even be lifting weights, working out, and whatnot at the moment, or should I just stay put and deal with all of this after the baby is born?