marvel - Why didn't this hurt Stark as badly as it did to Hulk?

In Avengers: Endgame

Hulk briefly wields all six Infinity Stones in the new gauntlet and screams in pain and is barely able to snap. It's also stated that he was the best fit for the gauntlet.

However

Stark later wields all 6 and while evidently in pain, is still able to snap with little effort and even says "I am Iron Man". While the snap does kill him, it doesn't seem like wielding them hurt him nearly as badly.

Why is this? Adrenaline, desperation, or something else?