Looking for ways to loose weight

So for starters, I have a thyroid problem, so it's not producing enough hormones and therefore it's hard for me to lose weight, but how can I lose weight now that I'm on medicine. I'm 5 foot 7 and 170 pounds due to the thyroid problem, I used to be 120, and I'm trying to get down to at least 140. Does anyone have any good exercising methods that I can use.