Jerome Kagan has a priod of serious depression. As a result he says,
"I took a private oath to make each day as beautiful as possible. Family, freinds, forests, reading, tennis, and exploring rich corpora of data have been effective defenses against the recurrence of that deep, dark melancholia"
It is a big wonder why this oath is not common to all people. Probably, rationality is not enough. Only a strong and effective experience makes people to invest in enjoying life.
Indulgence means to do things one truly enjoys for their own sake. Feeling free to move to the thing that is fun, and stopping at the moment it does not feel like fun. It is not work, it is fun.
Everyone has some free time, where he is having the technical ability to simply indulge in fun activities. One got to act upon it. Also, one must have a wide spectrum of things that he enjoys. Because moods and energy change. So that one can always truly enjoy the free time.
It may not happen on its own. For some people, having fun cannot be left for chance. (nor can one let fun be technically managed. It is a balance that is different between people and between days/situations)