After third son was born I kicked the depression but the weight is still sticking. I don't have any of preg weight left, so I'm sitting at 185lbs right now.

I currently walk/run or ride bike for about 20-30 min 6 days/week. I'm just starting to lift weights again after a one year hiatus using light wt(2-5 lbs) and an exercise ball.
diet is not consistent. I don't plan what we're going to eat day by day, which may be problem. I just go by whatever is in cupboard. I do have a freezer full of chicken(we raise our own) and beef(from the butcher).
Any ideas on how to kick the depression weight and gain back energy so that I can keep up with boys?
And why is this type of weight harder to lose????