What are the tell tale signs to move onto a new career?

I have been thinking about a new career joining the police force and getting involved as a police photographer. This has been in the back of my mind for three years, yet it's not something I ever imagined doing. I am bored with my current job as I've worked there for over three years and I know it inside out, it is in a related area of work. Joining the police would be moving away to another city and I would have to give up a lot of other things too, I feel it's stable in this time of life and a good positive change, I don't know why I'm apprehensive, possibly because it's such a big change to being a professional photographer, and I don't want to loose what I love. I believe I can still do both but I feel like I'm looking for a sign to change, everything else i've always done work wise has been with great pion. Maybe I just need a holiday for some time out to think?