I Become Winded When I Bend Over For Something As

I become winded when I bend over for something as simple as tying my shoes or vacuuming. I am about 20 pounds overweight and walk and play golf for exercise. I've had a chest x-ray and everything was normal. Ive noticed that if I eat a big meal, I get that sensation of the difficult breathing. Please give your thoughts as to why I suddenly feel winded when bending over. Thank you.