I need A LOT of motivation!

I've tried this diet/exercise thing many many times and I'm not too over weight but I've got a good 35-40 pounds to lose. I'm about 5'8 and I weigh 187. My goal weight is 150. I was 175 2 months ago but since then I quit smoking and ended up gaining 15 pounds on top of that. Reached 190 and then it really got to me. I use to be 160 and then I got pregnant and went up to 206. After having my daughter I was stuck at 193. I went all the way down to 174 and have never been below that. I really need a lot of motivation and advice! I have a gym membership and it has a daycare so I have no excuses not to go. Please feel free to add me. I'm sure your success will help motivate me! Thank you - Melanie.