Give, Expecting Nothing
This may be one of the hardest things to do in relationships.

A lot of times we think of this largely in terms of money. But what about giving of yourself; your time, attention and care / love?
Expectations can grow quietly, at very nearly a subconscious level, and assert themselves in strange ways. Unless we are vigilant, and remind ourselves of this often, we will attach expectations to our expressions of selflessness. And this puts pressure on the relational context, which can often be felt by those we have given of ourselves to, even if we are ourselves scarcely discern it.
This type of selflessness seems to require emotional maturity, which of course is not tied to chronological age. How can we demonstrate this key component of Christlikeness that Jesus demonstrated for us so well? We can recognize that selfishness is insidious and doesn’t die once and for all. It’s a perennial issue. We may well deal with this urge as long as we are in this life, and we should realize this doesn’t make us sinister, just human.
Also, let’s keep in mind that coming back to focus on the good of others, and the greater good, is a motivation that is effective, fruitful and benevolent. Focusing on our own good exclusively is a corrupting influence. It’s no crime to want good things for yourself. But to be fixated on this perspective becomes destructive, urging us to take for ourselves at the expense of others.
Having a mind of service to others (In love, serve one another. See Galatians 5:13) and reminding ourselves of this commission from the Lord regularly can act as a spiritual multivitamin, good for all our wellness. Serving one another in love is the essence of the resurrection life. Serving yourself is the essence of the fallen life.