I wore my Pro Trek PRG 40 during a SWAT challenge PT course, and it performed flawlessly. I used it to time my team's progress. At first, I was concerned that I would accidentally stop the timer, since it was a pretty physical challenge, but I never did. The course was 6.8 miles, with 18 difficult physical challenges, some of which required the watch to be submerged under water and mud. It even got banged around quite a bit. No problems at all. This challenge was 10X more harsh than my "daily life," so I am pretty confident the watch will never let me down. Think I'll by a G next.