He's talking about things like lust, or masturbation, not assaulting someone. Thoughts that you consider normal, are things that religious people struggle with.
I literally hated myself if I got horny enough to masturbate, usually upwards to half a year of repressing myself. I refused to pursue romantic relationships, considering myself not good enough, despite others showing very direct interest.
It's so stupid the Bible has so many big rules and this is a small interpretation, like the gay thing or the don't eat seafood thing or stone your slaves thing. So unnecessary