I got my first when I was 35 due to extensive history of Colo-rectal issues in my family. I've had 3 so far now with my 4th coming up shortly (every 3 years). While it is a bit nauseating to drink a gallon of seawater and then empty out, the procedure causes no pain and only consumes a morning from check in to check out.
Watching my uncle pass away from an aggressive cancer in less then a year and the impact to his body of loosing 150lbs was just a pointed reminder of what I already knew. I've only got one body, I can choose to take care of it and hopefully enjoy a long healthy life vs it being cut short by an agonizing and debilitating disease. If I do end up with something unfortunate like that, I don't want it to be through ignorance or inaction on my part.