To be useful

Some days ago I had a talk with a student of mine and her words reminded me of our need to make ourselves useful. I think it’s a very noble aspiration, but we risk the sacrifice of ourselves: how we can decide if a behaviour is "service" or not? Are a doctor, an hospital attendant, a teacher, a social worker, a psycologist... always in “service” of somebody? And a road-sweeper, a painter, a trader, a bus driver, a manager, an office-worker, a singer are not?
We need to pay attention to the others to be happy? I think so. And I think it’s important that other people pay attention to us too (I’m thinking about a song: I need a friend to be happy). But does this attention consist only in some activities and not in different ones? I think no. Well, if I’m lying on a beautiful beach and I’m enjoying the sun, my attention could be less evident. But also relax and self-care are essential to our lives. If I’m exhausted, I’m not so helpful. Indeed if I devote myself with passion to what I’m doing, to what I have to do and to what gives me satisfaction, I’m building the presuppositions of my utility, making myself happy.