A week ago, I was at a gala, and I ate a few chocolate truffles because they made me happy. I suspect it was wonderful, but honestly I don't remember if that was the case. Even worse, as I try to button up my pants and the pants are too tight, I'm feeling quite unhappy about eating the truffles.
In the above paragraph there were three "I"'s or "selves" being referenced. The present experiencing self, the future remembering self, and the future experiencing self. To concisely refer to these three selves we'll call them the experiencing self, the remembering self, and the future self.
As you think of three different selves there are two big questions. First, when you thinking about the costs and benefits of an action, think through the cost and benefits for the different selves. Second, decide which of the three selves you want to optimize for.
With luck your present self enjoys this post, your future self remembers enjoying the post, and this prompts your future self to re-read and enjoy the post again.