I’ve personally come to accept that feeling tired all the time is a normal feature of human functioning!
Busy lives, stress, high expectations of ourselves, borderline depressive symptoms, too much alcohol….
Not that this helps YOU much, nor is it at all a ‘proper medical opinion’, but in personal and professional life, often there’s no clear medical cause.
Those who spend their lives hunting for the cause, often exacerbate symptoms of stress and lethargy…sadly…
Anyway, I hope you pick up – these things can be cyclical. If it persists or is debilitating, your GP should be well versed in discussing this issue with you.
DrP