Same boat, I'm a 32 software developer and gamer, always spent most of the day on a computer, but since last year I'm very tired every day, I'm a father and doctors dismissed me as having some sort of midlife crisis or changes in my life even though from my perspective, I've never been happier, the only thing bringing me down is being tired. I sometimes feel dizzy when standing up, way more often and stronger than the natural dizzy you sometimes get when staying sitting too long.

The list of possible reasons is long and not all can be tested: long Covid, ME/CFS, diabetes, sleep apnea, depression, vitamin deficiencies.

I've tried to practice more sports, stopped all coffee and alcohol for a month, slept for longer, nothing changed, but I should continue some of this anyway.

There's also this documentary on long covid or me/cfs where some people have it so much worse, can't get out of bed like the Youtuber PhysicsGirl... Devastating.

Early studies seem to indicate permanent brain damage because of viruses like Covid, so there might be no chance of recovery, just learning to live with it.