Doing good with self interest?

I have been reading Desiring God, particularly the chapter about Love. It has been quite challenging as I read, I had to read and reread. It was about loving others but not quite selflessly but with self interest which is gaining joy as we do God commands. I think this is really new concept for me. As I grow in my spiritual journey, I have once been taught that when I cant love others (say helping them), just help them anyway and the love will gradually grow. I have always adopted that concept which I think it is fair because one do not have any capability to love as all of us are naturally selfish. The concept of Love without self interest, loving selflessly was argued to be unbiblical in the light of 1 Corinthians 13:1. It was said that one can give their own body to be burnt but if the person had not love, the person gain nothing. It seems that paul was suggesting that gaining something from loving is good. Micah (chapter and verse I forgot) said that we are to love kindness.

Love is not mere doing sacrificial action and yet Love is not only feeling either. It is a combination of both, having feeling in doing sacrificial action. The feeling of joy and delight as we do God's commands. Joy is given by God, and thus we should ask God if we do not have joy when loving others, when we dont feel like doing it. God will certainly give, God had answered my prayer. God delights when He saves us, loves us. If God just do those things without joy or delight then I think His love is dead.

Just a side thing, I am actually in the middle of running experiment for my project. Today's results did not agree with last time, at least for half of the samples that I have to test. I am really disappointed. I wish I was still excited because the result might tell me something new that I had not known before. However, I am really running out of time and I have to obtain good reproducible data from my replicates and now my replicates are showing a different result compare to the other days. Can you understand what I feel? I would just have to take a deep breath. Anyhow, I have managed to invite more friends to our dialogue lunch for Jesus Week. I'm really glad at least :). I hope they would consider to come.