I've been working in mineral exploration as a geophysicist for almost 20 years now. I was enrolled in chemistry my first year in university and very quickly realised that I would never see the light of day as a chemist. I wanted a profession that a) let me work outside; b) let me travel; c) paid a decent wage. Geology seemed to fit the bill so I changed to a combined geophysics and geology programme and never looked back.
The first couple of years after graduation were hell,
and I loved it. The work is not all that glamorous, the pay is low, and working conditions can be be pretty miserable. For the first ten years, I lived in a tent for eleven months of the year and worked in some of the most remote places on the planet (Canadian Northwest Territories, Nunavut, Labrador, Greenland, Alaska, Amazon, Andes, Scandinavia, Africa, Australia, etc...). 20 years later and I still love it. There is a lot to be said for truly enjoying what you do for a living!
If interested in this sort of work, there is potential to still be a technical crew leader (running a geophysical survey crew) without any formal training if you have the right stuff. As mentioned, in the beginning the pay is low, but you'll know right away if it's for you. You would work outside 99% of the time, in the bush/jungle/tundra/desert , and if you like to travel, it's hard to beat. PM me if you like and I can forward you some links to potential employers.
Good luck !!