The common or scientific answer may be that it is just the hypothalamus or pituitary gland producing hormones which tell the testes to produce testosterone. However, I feel perhaps that there is more to it than that. This community has a lot of interesting ideas about psychology and sex, so I wondered if there is a more accurate explanation.
For example, there are many people are are totally ok with going without orgasm for days or weeks, while for others, lust is a lot more noticeable.
Also, I found that lust tends to arise particularly after periods of stress, and it compounds with previous instances of lust. For example, if one has thoughts of lust, then during the next day one is bound to have even stronger thoughts of lust, etc. And this lasts for a long time, which is odd because testosterone supposedly has a short half-life.
Thanks for your time