To the OP
There have been lots of replies that have had useful advice given IMHO. Sadly many of the outdoors type jobs do not pay very well at all, but that was not part of your original question.
I have done various outdoor jobs part time and enjoyed most of them.
The worst job by far (at times) was being a survival/bushcraft instructor (for civilian clients. The military courses were more fun). There were some lovely clients, but also there were an awful lot of Ramblets, and Gryllets (rambo and bear grylls wanabees), who arrived, with no knowledge, but were 'armed' with huge knives.
It was good when the students were good, and leading expeditions could be good to, but repeatedly teaching the same skill sets over and over could be tedious and mind numbing. Oddly, as I was needing to constantly keep an eye on the students, I also got to see less of nature than when I lead group walks or volunteered to do dry stone walling.
If you do decide to make your career an outdoor one, then outdoorsy qualifications will always be an advantage. When I chose not to work in outdoor environments (I worked seasonally) I had a degree and diploma's in other areas to fall back on.
Edited to add: there were of course humorous moments to teaching survival too. Despite being given extensive guidelines on what to bring, many students would bring a carrier bag to carry their gear in, and at least once a year, a female student would turn up wearing stilletos!