Alright, leveling up your strength is actually fairly easy first, you have to get a friend and tell him to stay In the car while you punch the sh*t out of it this will get your strength stat up in no time.

Lung Capacity: for lung capacity get a SUV or the big four door trucks and drive to the ocean at a curve so the driver window will be facing the ocean. Drive it so it's just over your head you will keep breathing because the waves move rapidly.

Stealth: all you have to do is go into "stealth" mode and walk around in circles, what I find easy is to get a rubber band and put it over you Left stick so it moves by itself