Right, where to begin with this?
There are various ways to work in the fitness industry, so I suppose I should go through a few (brace yourself for a long post). I’ve worked in the industry for 15 years now, so here’s my two penn’orth.
1. Fitness Instructor: Getting pretty rare now, mainly to be found in Local Authority leisure centres, though becoming an endangered species there too. The Instructor jobs in the private sector are shockingly poorly paid and are generally filled by school leavers or people wanting a part time job. The public sector version is better paid, but you won’t have to worry about top rate tax brackets.
You can boost your pay by taking extra qualifications (Exercise Referral etc.), or becoming a Group Exercise Instructor (formerly known as classes until managementese took hold), you can either take these off shift or on; your pay should always be at the class instructor rate.
2. Personal Training: I’ve no experience here, but it’ll depend on where you locate to as to what your potential income will be. Richer areas will obviously give a higher income, but your rent for facilities/parks etc. will be much higher too.
If you work in one of the chain gyms, you’ll either pay rent to use the gym, or give them free hours for inductions, cleaning etc. which is where you get to introduce yourself to potential punters.
Personal training needs business and marketing skills, probably more so than fitness knowledge; if you can’t get clients, you can’t train them.
Prepare to be appalled by the shower of King Cnuts that most civilians are when it comes to their attitude to exercise. I’ve never been in the forces (I was browsing the site for info about the PARA 10 when I saw your post and helpful fella that I am…), but I expect most who have can generally be relied on to at least turn up and train more than once a month. Nor I expect, will they tell you how much they hate it but refuse to be coached to make it more rewarding.
A good route in to PT could be working at British Military Fitness classes, they’re always popular and you could always get clients for PT through it as well.
3. Leisure management is a better paid alternative and one that often lets you pick up clients for PT as well, ones that you select for yourself too, not the aforementioned Cnuts. Military man management experience at whatever level should transfer well I’d imagine.
Liking fitness is a start, but you’ll need to see exercise from the average salad dodging customer, who may well have done no exercise at all for a quarter of a century or more; you will seem almost alien to them.
Have you considered going to Uni to study Physiotherapy, and taking classes (Metafit, Spinning, BMF etc.) as income?
Hope this has helped a bit and any questions etc. just post em up