You're quite right. Passion is vital to any effort to persevere. If you don't have the energy or sense of vitality, which is something I struggle with constantly, to struggle on amidst difficulty, then the effort will not feel worth the reward in the end. At least that's my opinion. I look back on my life and see a lot of wasted effort because I didn't have the wisdom needed to go against the conventional grain, and I wouldn't wish that on anyone.

Introverts suffer a lot in this respect because society demands constant engagement. Society should take a cue from introverts and slow down a notch or two. I read a decent book in this regard by Susan Cain some years back. Maybe it can do you some good as well.

https://susancain.net/book/quiet/

She did a Tedtalk as well which I found interesting.

https://www.ted.com/talks/susan_cain_the_power_of_introverts