For me its not that I don't feel like doing work on most days. Instead I have periods where I am super uber productive and days where I feel completely exhausted. I can't tell if its a mental thing or rather there's actually something physically wrong Lol. My mind tends to be blurry like its rebelling and if I force myself to work hard I start feeling feverish. I have trouble figuring out if I'm not working hard enough or working too hard.
I wonder if its also like that for some of the successful startup founders out there too