Loseing 40 pounds before august?

Well before my feshamn year, I wanna weigh 160. Right now I'm about 200 pounds. I ride my stationery bike in my basemet 4 times a week, which is the only time of the week I have access to a exercise machine. I eat breakfast lunch and dinner. I keep track of all my calories on my iPod. Is their anything else Ican do?