[I asked] Cohen about longevity in songwriters, why so few lasted past adolescence.
I think there are a number of things that bear on that. You can burn yourself out, for one. The late teens and twenties are generally the lyric phase of a writer’s career. If you achieve enough fame and women and money during that period, you quit, because that’s generally the motivation. I mean, I didn’t get enough money or women or fame for me to quit. I don’t have enough yet, so I’ve got to keep on playing. I know it’s rather unbecoming at forty to keep it all going, but I have to do it.
The Obscure Case of Leonard Cohen and The Mysterious Mr. M. by Bruce Pollock (After Dark: February 1977). Found at LeonardCohenFiles.