You must be deep breath huffing and puffing.
Or biking, rowing, swimming, etc.
My co-worker (two years younger than me) was the fittest person I have ever known. His daily running diary fell 13 days short of 17,000 consecutive days running 5 miles or more. Most days included bicycling 15 miles to work, after work "wallyball". He was on the corporate running team and often ran marathons. The break in consecutive days was a consequence of a sprained ankle playing "wallyball".
My co-worker died of massive heart attack at age 44 on April 16, 2003 at 2 AM. The ambulance arrived promptly at his home, but he was dead before he could be placed in the ambulance for transport.