I worked as a commercial SCUBA diver on Lake Tahoe and in the Truckee River for the past 6 months - and though this was my job ostensibly, it was all part of an extended road trip and "vacation" of sorts. My company, operates out of Oregon on local, state and federal contracts around the United States and even abroad. They're environmental cleanup and marine ecology experts and are, plain and simple, some of the coolest, most honest, fair, knowledgeable and **bleep** respectable collection of human beings I've ever met. They, more than anybody I've ever known, taught me how rewarding extremely difficult work can be when the pressure, literally is UP.
I'm a 30 year old, very physically fit guy and I got my butt handed to me every single day pulling out invasive Milfoil species, a type of aquatic plant that has taken over many lakes and river systems around the world and is now gradually polluting our majestic and extremely deep Lake Tahoe and its sole outlet, the grand and long Truckee River. The work we were doing was a rough-going, long and arduous and extremely cold underwater form of gardening I guess you could say. We were working with dredges and hand-tools to weed out this incredibly cool, resilient and tenacious species of plant that had probably been introduced to the area in the 1980s through carelessly wanton dumping in the South Lake Tahoe area known as the Tahoe Keys (it's an ecological dump - blame greedy HOAs, motel/hotel and casino jerks...).
Every day, we would put on our heavy gear, overweight ourselves to stay firmly anchored to the bottom to get our work done, and work, continuously, at depths ranging from near-shore to 40 feet down for 6 hours a day in 48-degree water. I wore a $25 used 7/14 "Farmer John" wetsuit and learned how unflinching and fair a teacher the cold can truly be. I also learned where my limits are at and I learned that I, like my amazing and tough-as-nails colleagues, are pretty mentally-hardened. The feeling that you get when you're in a very small and select group of individuals doing something literally nobody else is doing, day-in and day-out, is not rewarding; it's life-sustaining, a true treasure. Humans are amazingly capable, dynamic, natural problem-explorers with a knack for endurance we all tend to underestimate.
All I can tell you is this: If you want to see truly how far you can go, you must realize your certifications and your trophies and your badges mean nothing. What really counts is grit and you don't ever buy that. True grit is earned when you have had more than enough to kill you and you make it out more than alive; you make it out with a smile and the knowledge that allows you to know truly, "Hey, I'm pretty awesome and I can overcome so much. I own that and you can't take that away from me".
May your travels always lead to unexpected insights and profound new realizations,