26 years old. high school athlete. not active for past 5 years. light headed, weak legs, cloudy vision, hard to breathe during exercise. what's wrong?

Physical: Although you are only 26,you should get a complete physical exam including bloodwork.If all is good, then probably a matter of starting a planned and monitored training plan,starting slowly and building to your goal, whatever you decide it to be.This would serve as a baseline.If problems are noted, then you and the Dr. will develop a plan.Check your hydration- likely partially dehydrated.Good Luck

Lack of exercise: may cause blurred vision, dizziness, fatigue and muscle weakness. Because these symptoms can be caused by many other health problems, the visit to your PCP is warranted.