I first got NAUI certified in high school, and then couldn't continue because I was a poor kid who couldn't buy equipment. And then about 15 years later I went back to it. This time PADI and up through divemaster. Stuck with it for several years, and then life intervened. Kept all my snorkeling gear and sold everything else.
In the back of my mind I think I'll get back to it someday. I sure hope so because I enjoyed it , especially after I figured out how to actually do it. Which brings me to the comment about the one-legged guy not being very fast underwater.
I think the biggest mistake that most people make diving is they think it's an underwater version of hiking. They go down and try to cover as much ground as possible, thinking it's going to make a good dive. Usually the reverse is true. One of the best dives I ever had was a time when I went down to the bottom of the anchor line, just held onto it, laid on the bottom, and didn't move until my air was nearly gone. I saw more interesting marine life in that dive than all the others.
Tom