There is danger in thinking of only ourselves.
Happiness does not come from being self-absorbed. In fact, I would argue that we are happiest when we serve others. But service doesn't have to mean never taking time for ourselves. And conversely, taking care of ourselves doesn't mean there will be no time for caring for others. Perhaps this quote sums it up best:
"The best way to find yourself is to
lose yourself in the service of others."
~ Mohandas Gandhi
Taking time to care for ourselves allows us the energy and motivation to serve others. However, it can be consuming. When you feel like you must always put your own needs first and become self-absorbed the good you were doing by taking care of yourself dissolves and unhappiness will be the result.
This is where listening to our bodies comes in. Perhaps today all you need is a quick shower, a healthy breakfast, and then someone to serve. Tomorrow you may need to stay in your pjs all day reading a good book. As you learn to trust your body you will know how much energy you have for service. But know that service is contagious. At first you may be resistant, that's normal, but as you learn to care for others you will find joy.
In my own life, as a teenager I spent a lot of time serving. I can honestly say that I was happiest when I was in a nursing home visiting with people, or weeding someone's lawn who was in need, or cleaning the house before my mom got home from a trip. Service doesn't need to take all your time, but I can promise that you truly will find yourself and find complete happiness when you care for those around you.