Help! I need to lose like 20 lbs quick, I know everyone asks how to do this in an unrealistic timeframe but..

I am willing to put in the time it takes, but I need to lose it, I was running back in the summertime but now that it is chilly, it really hurts my lungs to run. I have a gazelle that I can also run on, but how much good does that actually do? I love food, so I don't want to starve myself. If there are any ideas to help would be GREAT thanks in advance for your help!!