volunteer

discretionary, elective, optional

impulsive, instinctive, spontaneous, unpremeditated

conscious, deliberate, intentional, knowing, willful (or wilful)

chip in, kick in, pitch in, throw in

award, confer, endow, endue (or indue), render

afford, comp, furnish, provide

lavish, regale

aid, assist, benefit, help

administer, dish out, dispense, dole out, hand out, impart, issue, mete (out)

extend, fork (over, out, or up), offer, pay, proffer, pungle (up), put up, tender

sacrifice