Good question, but needs to be worked through more.

Consider an average person's 72/min resting heartbeat. That will be (726024365.25=) 37,869,120 heartbeats per year or ~379 million/decade.

Now, add strenuous running or cycling 5 hours/week, maybe a 10mi run, and a bunch of 20-60 minute runs. Call that average 180 beats/minute. That adds ((180-72)30052=) 1,684,800 beats/year, or +16 million per decade.

The average person's 37,869,120 beats/yr divided by the exercising person's 27,349,920 yields a ratio of 1.3846. So, based on heartbeat count alone, the exerciser will live 38% longer.

BUT, this kind of training will dramatically reduce the resting heartbeat. Training far less than this, my resting heartrate declined into the high-40s-low-50s, and has remained consistent for decades of mostly maintenance training. Most recent six month average is 52 beats/min. with far less than 5hr/week training, but let's use that. That means the resting heartrate is 27,349,920 beats/year, plus the added 1,684,800 exercise beats, making it 29,034,720 beats/year or ~290 million beats per decade.

That means the exercising person 'spends' 8,834,400 FEWER* heartbeats per year, or saves 89 million heartbeats per decade.