Observational study of people self-reporting their exercise regimen and mood (depression) found that those exercising 3-5 days/wk has 1.5 days of poor mental health per month.

Health Headlines Commentary for November , 2018

Source:

Exercising 3 to 5 times a week brings biggest mental health benefits

Reference:

Association between physical exercise and mental health in 1·2 million individuals in the USA between 2011 and 2015: a cross-sectional study