I don't consider myself to be selfish.
I spend a lot of solitary time, recharging, but do nice things for others, when I associate with them. On many occasions, I've donated: to homeless people, charities, and those short on blood (I gave mine). If someone would like help, and I'm capable of helping them, I will.
You won't see me spending 12 hours a day undertaking some social action, unless it could be done with minimal socializing.
I enjoy and value helping others, but if concomitant conditions of helping them (eg. socializing, tumult, expected façades, crowds) exhaust me, I have to bail out and breathe, for a while.
When analyzing one's position on the selfishness-selflessness spectrum, one should consider not only what is done for others, but WHY it is done. Is good done because you believe in others' wellbeing (altruism), or is it done to get rewarded and/or be liked (sycophantism)? On one extreme, there is hedonism (self-indulgence independent of others' needs), which is not necessarily evil, unless it is a form of parasitism (A benefits; B suffers).
I alternate between altruism and hedonism, whereas some so-called "good" people pursue sycophantism. Sycophants only do good for others to manipulate them into reciprocating. Ugh! Yuck! I consider sycophantism selfish. Some of the most fulsome people are sycophants.
Hedonistic activities can be used to recover the energy, morale, and happiness needed to pursue happiness. When one has sufficient energy, one can then unleash altruism. That's my style. I can spend 10 hours on my computer, then go donate blood. I: walk into the clinic, am assessed, donate, then leave. I feel good by knowing that I kept someone alive. I don't tarry, to be revered; I know I did something kind. The reward? Love, rather than excoriation, from the scruples within me.
For how long can I help? Probably, for as long as people don't exhaust me! Bureaucracy also tends to drain me; I'd rather design a plan or strategy for helping others. Conforming to the minutiae and etiquette frustrates me, because I feel stupid, when following rules (rules of: mathematics, programming syntax, and grammar might be the only exceptions). I'd rather: imagine, design, and defy. I don't mind mapping out a plan, but I hate following plans thrust upon me, because I'm then forced to memorize steps and brainlessly obey. I'm a free spirit, and following rules makes me feel subordinated and enslaved.
If you're a Chaotic Good, on the Dungeons & Dragons Alignment grid, you'll probably relate to this.
Anyway. Rant complete.