Past few days been hacking up clear white mucus with a little trouble breathing and getting lightheaded when i walk i am obese just started exercise?

Cough: If otherwise healthy apart from obesity these symptoms will lessen and resolve with time,meantime moderate your exercise a little and gradually build up to a higher sustained level of exertion for cardiovascular conditioning and weight loss incorporating a carbohydrate and calorie restricted diet.If persistent over a longer period of time then seek physical examination to begin an assessment.