Any way to lose 70 pounds in 7 months?

I want to lose 70 pounds by next birthday, August 23. I am 5'2 and weigh 210. I am purchasing a Gazelle Edge Trainer next month, I did research and it sounds like a good choice. I can't afford a gym membership, and I live in a somewhat bad area. Any tips? Ever since I had a baby, I have been fighting my weight. I used to weigh 140. Now my kid is 4 and I still can't lose the weight.