One of the things I've wrestled with is donating money. I feel that I'm overcompensated for what I do and I have a responsibility to redistribute some of that money, but it's been very difficult to open the purse strings. Donations are probably 4% of my spending currently, which is IMO way too low. I'm ratcheting it up in increments, but even those feel tough sometimes.
Compare that to my partner, who is very frugal but has no desire to retire early- she set her goal to donate an equal amount to all her nonessential spending (travel, restaurants, entertainment, etc.) and usually achieves it. So I think the accumulation mindset is a big part of what's getting in the way of charity for me.
And yes, you can say "put on your own O2 mask first", but there's people who are hungry today. There's political change that could be effected today. Do I really want to be the sort of person who makes sure I'm absolutely, completely secure before I'm willing to help folks in dire straits? I don't think so.