I worked in 1 WTC and was about to get into the elevator when the first plane hit on 9/11. I was outside on the corner when the second plane hit.
When my head started to clear some time later--a week? two?--the clearest thought I had was: if my last act as a human had been connecting a data input form to a database table, it would have been a tremendous waste of my life.
Shortly thereafter I entered a new career and a new trajectory through life. The last 10 years have been amazing.
Living with the visceral awareness that sudden death is possible has changed me in many ways. Mostly for the better.
I do have some symptoms of PTSD. Low-flying planes freak me out intensely, as do sudden loud noises and low vibrations strong enough to shake things.
On balance, though, it has catalyzed tremendously positive change in my life. I'm glad that you've been able to make the same of it.
Cheers to being alive.
(Bizarrely, I was also in London on 7/7. A bomb squad truck nearly ran me over (on my bike) going the wrong way down the road near Liverpool St. station, and my wife was very nearly on the Hackney Wick bus.)