In every relationship, in every act of love, there is something we give up. Economists will call it opportunity cost. I simply call it the gift of giving.
Me being a generous person (it's all I have you know, it's not like I'm handsome, or intelligent, or charming, or talented), I've deliberated on the subject in the past. And the conclusion that I've come upon is that when you give, it should be done out of love. Because honestly, if you're looking for compensation, it'll never really be enough. Thoughts like "if I give this to her, will I get a kiss?" or "if I do this for her, will I score some points?" will, in the end, be counter-productive. As I said before, it'll never be enough, and what happens when you don't get what you want, take the gift back? (Which is also why I don't believe in returning of gifts during a break-up; I know it reminds you of painful memories, or that it cost a lot, but it is a gift after all and not a pre-nup.)
And perhaps the important thing to observe before you give are your intentions. Are you sincere about it? If so, then go ahead. I've given gifts to people who in the present loathe me. And while I'm tempted to think on what I could have spent my time and/or money on something else, I simply don't. Because I know my intentions at the time were in the right place, and I'd do it again if I could turn back time. It's part of living with no regrets. Give out of love, not because of what you could get.
St. Paul (yes, yes, you devout Catholics and Christians can footnote that it was inspired by the Holy Spirit and God) said it best in 1 Corinthians 13: 4-7. "Love is patient, love is kind. It is not jealous, is not pompous, it is not inflated, it is not rude, it does not seek its own interests, it is not quick-tempered, it does not brood over injury, it does not rejoice over wrongdoing but rejoices with the truth. It bears all things, hopes all things, endures all things."
I don't care if you're a Christian or not, a believer or not, a good person or not. There is, at the very least, wisdom in those words if you take the time to process them. It's not even about being a good Christian, but about being a good human being, and doing what's best for you. If every act of "love" is something we sought something in return, then I doubt if you'll ever find happiness (as if "love" was equal to "happiness").