At 66 I don't care how fast I climb any more but just 15 years ago I was one of the best climbers in the group because at 5'5 I weighed only 125 pounds. This is huge! It's simple physics. Your heart is just as big as someone who is six feet tall so If you stay lean it pays big dividends. By the way, it's about 70 percent mental so don't quit as soon as you ride into the house of pain. Embrace it! Attack it! I used to do repeats on a mile long 9 percent grade hill on weekends so on the Wednesday night rides I could kick ass. Do a bunch of repeats on the steepest hill you can find and then go home and rest. Don't go on a long ride afterwards. The house of pain likes you if you visit often.