Selflessness is never truly absolute. Why? Because we must obtain for ourselves power, spiritual gifts, and knowledge which we can use for others. It also also right to rejoice, rest, and play. Some of the greatest acts of love consist of simple play.
However, most of our lives and most of our times will be devoted to serving other people if we love God. Therefore, it is useful to inspect where our motivation for this altruism can come from.
The more we are motivated by discipline stemming from an abstract to-do list, set of expectations, or commandments, the quicker we will become weary. Psychologists are researching a new theory called "ego depletion," which states that discipline drains a person's energy and that people only have so much capacity for discipline. This theory at least partially accounts for burning out, cycles of addiction, and general low energy. Of course, service from discipline is better than nothing. However, it is often typified by high stress, either arrogance or discouragement, and perfectionism.
Service from love is typified by joy, satisfaction, and happiness. It also involves more meaningful prayer, greater sincerity, and less self-focus. If a person serves out of love, others will feel it. When others reject their love, they are hurt and disappointed, but they don't feel worthless or discouraged. They keep on trying. I believe that is how the Savior feels about us.
Discipline has its place. It must have taken all the love and all the discipline the Savior possessed to keep going through the pains of hell (D&C 19:15-19). Because He had no lack of love, discipline took its proper place as He kept His vision and His determination.