Other unrelated studies on weight lifting and high intensity training put the differences at around 20%. I'd consider weight lifting and HIT/HIIT 3-5 times a week to probably be more effective at producing these results than a job, obviously depending on the job, so likely an upper bound of 20%. Obviously a big conjecture here.

Other interesting results from various studies on improving testosterone also show around a 10-20% change in testosterone due to various stresses on the body:

  - higher carb diets (200+ grams carbs per day) produce ~20% more testosterone
  - vitamin D deficiency linked to ~20% reduction in testosterone
  - 5 hours sleep per night over 10 days linked to ~20% lower testosterone
  - excess cortisol due to stress linked to ~ 10% lower testosterone

I got interested in this due to finding out I had pretty low testosterone levels. I am a chronically sleep deprived dad of 3 with a stressful job, so it wasn't a surprise. Working through that list myself and running some experiments to see if I can improve levels naturally, and if so, if the above list has any stacking effect, or if there's maybe just a 20% hit due to body stressors, regardless of the stressor.