The frequency and passion that the word "selfless," as in a"selfless act," is used may cause a person to think the best acts and best life are ones that never think about the value or care of self.
It may cause a person to serve to the extent that is unhealthy overall. Serving to the extent of not taking care of one's self over a long period of time is not good. By taking care of oneself, I mean taking times to rest, eat enough, and recreation that refreshes.
It's true that the best acts are not solely focused on one's self. But it doesn't mean that the self is denied completely. It's not an either/or situation, but a both/and. It's more thinking about both--more than just self.
An example is shared enjoyment at times because you brought someone happiness through work even though it was tiring. Or knowing you have value because of God's part of giving that value to created beings and, especially to those who have access to him in Christ, and God's guidance and care of their everyday lives.