Bruce spends fifteen minutes every day thinking about the lowest points of his life. He sits in half-lotus and remembers being so wrung-out he could not even stand, reduced to literal rags and begging, his watch, shoes, hat, clothes, wallet and tiny accumulated store of cash, backpack, and worst of all, the laptop and his painstakingly scavenged equipment all gone, every little bit of comfort and hope he'd managed to scrape together just vanished like water down a drain. He remembers coming to in the freezing cold with a misshapen bullet in his fist and being so filled with despair and disappointment that he'd allowed himself to freeze to death a couple of times before he finally got up and figured out what to do next. He remembers seeing Betty in a hospital bed looking barely alive and knowing that he had finally done what he swore he would never do, what he had been so afraid of doing since he was six years old and watched an ambulance that didn't bother with the siren take his mother's still body away.
He thinks about these things because otherwise he starts to take his situation for granted. Luxury is to Tony Stark as water is to fish, but Bruce can't afford to be so complacent. In such a sheltered environment, little things can start to bother him: the barrista taking two minutes longer to fill his order because she's flirting with the guy in front of him; the constant barrage of high-volume heavy metal that Tony surrounds himself with; that pipette he needs not being where he's sure he left it. If he lets them, all those tiny daily irritations can slowly start to seem important and his baseline stress level starts to inch upward. There is so much that he cannot control but he absolutely refuses to end up killing someone over his Starbucks order.
He does a little bit of volunteer work at a homeless shelter, too, trying to pay back some of those alms tossed into his outstretched hands when he was so desperate. It took Tony all of three weeks before he realized that Bruce was disappearing at the same time every Tuesday morning and suddenly the shelter was the recipient of an extremely generous grant from the Maria Stark Foundation. Bruce surprised himself with his reaction to that one, having to sit in a park and breathe for three hours before he could trust himself to talk to anyone at all, much less risk seeing Tony. It was just such typical Tony arrogance wrapped in a barrel full of good intentions. Bruce understands that even Tony's money wouldn't outlast trying to fix everything that was wrong with New York City, much less the whole world, but just the idea that this particular shelter, these particular people, were only worthy of the great Tony Stark's beneficence because his friend happened to choose their shelter at random just pisses Bruce off. There are days when the Tower's endless, clean, hot water pisses him off, too, when grocery deliveries and artisan cheese and microbrews make him furious. But mostly, as always, he is angry at himself, for staying in Candyland when so many people who deserve so much better than he does have so much less.
But he's thought about it, incessantly in fact, and he can do more good from Stark Tower than he can "walking the earth", as Clint calls it. He directs Tony's donations to where he thinks they'll be most efficient and does the lab work that he hopes will eventually at least make a beginning at leveling the scale. He suits up with the Avengers and prays to gods he doesn't believe in that the Other Guy will listen to Steve and remember to smash the right things. It's all a precariously balanced mess, predicated upon good luck and wishful thinking, two things that he always scorned when his life was much more predictable. But it's what he's got, and it's so much more than he dreamed of having at his lowest points.