This all makes perfect sense. I'm 61 and went from 280 to 540 in a pretty short time. I do the following:
1. Sleep 8-10 hours a night
2. Sunlight exposure (no shirt, sometime shorts) 20-30 minutes a few times a week. I just walk around my industrial area at work. I generally do it barefoot to toughen my feet for international surf trips. It also provides "earthing", which doesn't raise T (that I know of) but has lots of benefits.
3. NO prepared foods. All fresh. Generally meat proteins (lots of venison, beef, pork, and some limited chicken, since I am a bit allergic to chicken) and veggies.
4. Alcohol = less than one drink per week
5. Moderate exercise 2 -3 days a week (lifting 50 pound sacks of salt for my job, etc.)
6. Extreme exercise about 1 day per week (off road dirt bike for up to 2 hours on hard trails)
Of everything I do, I would say 1, 2, and 6 have by far the most effect on how I feel. And I believe how I feel reflects my T levels.
T is on the horizon, but we're not there yet.
NOTES:
Sun: Sunlight exposure can raise free TESTOSTERONE by up to 69%. There is mounting evidence that sun exposure in the absence of sunscreen
decreases the rate of skin cancer. Australian lifeguards have the lowest rates of skin cancer in Australia. The highest rates of skin cancer in the UK occur in office workers who have little to no sunlight exposure.
Vitamin D is likely the most significant steroid hormone that raises free testosterone in the blood. And sunlight is the most efficient method of increasing this hormone.
Sleep: The majority of the daily free testosterone release in men occurs during sleep. Poor sleep significantly reduces testosterone.
Exercise: In older men HIIT seems to be the most effective type of exercise for non-transient increased testosterone. Probably why I feel so much more manly after riding the dirt bike.