This [1] is a study which attempts to quantify the diminishing returns of exercise. Compared to no exercise, people who do 1-2 times the recommended 75 minutes

This [1] is a study which attempts to quantify the diminishing returns of exercise. Compared to no exercise, people who do 1-2 times the recommended 75 minutes of weekly intense exercise or 150 minutes of moderate exercise have a 31% lower chance of death across a median 14 year follow up period. Those who complete 2-3x the recommended amount had 37% lower and 3-5x a 39% lower chance. There was no sign of negative effects of 5-10x the recommended amount, however no additional benefit either. https://www.ncbi.nlm.nih.gov/pubmed/25844730 https://www.ncbi.nlm.nih.gov/pubmed/25844730