I've always been very inflexible and it never bothered me until five years ago. Flexibility began to transpire as the missing link to my climbing improvement. Since then, I've taken up acro-yoga. I'm quite fit. In four years of training, my "front bend" (=reaching down, standing with legs straight) improved from "I can put my palms to my knees" to "hands almost flat on the floor". This is massive and it took very many hours. It also leads me to believe that given time and the right exercises, I might be able to do basic splits some day. Then again, I'm 35. and I've never been a bit flexible. How far can I go? This Tom Kurz summary didn't answer my question. I'd be happy for any advice and evidence on stretching. I already manage to do stretches almost every night (It's awesome!).