>>5551>interest in the army and the navy>don't revolve around harming others
Well, there's the merchant navy, but as someone who is part of it, I would strongly advise you not to get involved. Let me elaborate.
They will teach you discipline. You will inevitably harden up. You will live the archetypal military life but without guns and fighting. And the money is really good, too. But then, once you are in, you will see an entirely new world of elitism, bureaucracy and corruption. From your superiors to the authorities, everyone's out there to not to let you do your job, and then blame you for even the smallest mistakes. You will be locked in, for months, with around 5-25 people, depending on the ship. And only 1 or 2 of these might be actually good and understanding individuals, the rest will be cold, rigid, burnt out human wrecks who always want to know (and do) better than you, and regardless of their rank, they will work hard to get you out of the way. By the first few weeks of your contract, you will have even the slightest optimism and motivation drained out of you. After a while, you will feel like you are a prisoner out in the middle of nowhere. After a while, you will realize that you are not even able to smile anymore. And shore-based people ("landlubbers") will not understand you. I lost practically everybody since I started this career, as the couldn't cope with me slowly becoming salty and life-weary, like pretty much all the sailors out there…
>I was thinking about becoming a fireman
Take this with a grain of salt, as I have some mild pyrophobia going on, but even with that aside, I believe this is unique among the "disciplined civilian" professions as it's demanding both physically and emotionally. And I mean EXTREMELY demanding. As you described yourself as "squeamish", I wouldn't suggest you this one either.
>or a park ranger
Now this sounds much better! (Implying you actually meant a forest/field ranger, and not a park warden.) Though, depending on the country you are from, you might still be armed (but, from what I understood, that itself would not be an issue for you), it's definitely the most peaceful choice. And to be honest, something that I would take up as well. Not quite as militaristic and orderly as some of the other options, of course, but, once you get used to being constantly exposed to the elements and nature, you could actually have a rather pleasant time.