Problem with bouncing while exercising?

i recently got a gym membership at the YMCA, mostly because the one near me has a ton more machines and other facilities that the other local gyms, well here is my problem, when ever im jogging of running on the treadmill, my bounces... usually i wouldn't really pay much attention to it, except the Y that i go to is mostly the elderly... needless to say its a bit embarring. i didnt pay much attention to it until i was jogging on the indoor track and an old woman gave me the most horrified stink eye ive ever seen! my question is: Does anyone have some tips to keep my in check? thanks.