Finally Motivated!

Hi everyone! I am very happy to find this forum as I am really getting involved in the fitness lifestyle! A little background on me: I am 24 and I was always the thin, healthy, in shape kid growing up. I never even thought about my weight or doing special things to workout. I ran everywhere, and looking back, I can't believe the endurance I had!! I lived a lot of my growing up years on a farm, so the farm work I would help out with really helped keep me strong. My mom was a huge health food nut, so I always ate as healthy as could be. Well fast forward to when I was 16 and ended up pregnant with my first child. I gained 60 lbs with pregnancy and only lost 30 of it after I had my daughter. I had no idea what to do to get back into shape, so I just ignored it. Then 2 1/2 years later, I had my son. I also gained 60 lbs with him, and I was a whopping 180lbs after giving birth(I started out at 118lbs pre babies). I ended of losing a lot of the weight in a very unhealthy way, and I'm stuck at about 145lbs, and I am as untoned as it gets! So now, after several half hearted attempts at getting in shape over the years, I am finally getting serious! I'd like to lose 15-20 lbs and tone everything up, especially my midsection. All tips and encouragements are highly welcomed!!!!