Thanks for the suggestions, everyone.
Excellent post, Redwood. If “doing it for yourself” meant only “that it is for your own benefit (even if that benefit stems from the opinions of others)”, then I would understand easily what was meant by the mantra, and I would be surprised if anyone didn't PE for themselves. But some of the other posts here seem to indicate that something more is meant by “doing it for yourself.” Trigger & Muttley pointed out one tangible aspect of the “something more”: a bigger dick will make sex feel better for YOU, too, and not just because of the excitement of giving your partner more pleasure. (Bigger dick = tighter pussy.) Another aspect of the “something more” given here was to restore good erections, which of course will also directly benefit your sexual pleasure.
Any more suggestions about direct benefits (i.e., unrelated to other people’s thoughts, pleasures, etc.) from PE?? That’s the question I’m asking here, if I wasn’t clear the first time.