The relationship between exercise and testosterone levels is not widely appreciated. Exercise--especially HIIT and strength training-- will boost testosterone levels.
First, testosterone levels are highest in the morning and are subject to circadian (light/dark) variation. Measurements of testosterone levels should generally be made at peak, that early morning.
Second, exercise can layer on. Mr. FL just has his annual physical and blood work. On this occasion, he rose around 0600 for a 90 min workout--elliptical and upper body strength--showered, and went in for the blood draw. Total testosterone--at age 66-- was 580.
The importance of maintaining fitness through regular really-break-a-sweat exercise cannot be overstated.

