Some people just have higher constitution stats. Picard is maxed out. Service and duty above all else, no matter the cost. Even if that cost is a part of himself.
I do love the episodes where he just cracks. The one after Best of Both Worlds when he’s hanging out at Chateau Picard with his family? Fantastic. Seeing him break at the end. First Contact as well when he loses his fucking mind. We kind of need that sometimes because if this dude who can survive anything is fracturing then what the hell does that mean for everyone else.
Lowkey that’s also why the alternate Riker that’s being chased by the borg spooks me so much. Seeing him desperate and terrified… fuck. How bad was that world…