Shortly after my rookie year I was standing in the locker room talking to JW, getting ready for our briefing. Out of the corner of my eye I saw a chubby fellow standing off to my right. Glancing over I was stunned to find the stocky lad was, in fact, me reflected in the mirror! Whoa what the heck was that gut? Where did that double chin come from? Dang, the jock I thought I was wasn't the dude standing in the mirror next to me. It was a side view I hadn't actually taken time to check over the last year or I would have seen the transition that was happening.

I was just used to being in shape, looking as good as I could benching a pretty good chunk of iron. But now…something had happened. What had happened was police work, graveyards for a year, eating at the only place open in my beat (a Jack in the Box with those awesome tacos and breakfast jacks), and missing a lot of basic workouts. I had gone right from college where I played rugby and worked out constantly to the academy. Physical training as a cadet had kept me in shape when I hit the streets, and I was certain I would have no trouble maintaining my 22-year-old physique.

Like many young crime fighters, I was living the good life, suddenly making more money than ever before, with a retirement already planned and a great medical plan. I was low debt, low maintenance, and living the greatest adventure of my lifetime. So I decided to get a spouse, a house, and a new car and suddenly I was high debt, supporting two, and grabbing off-duty jobs. Still a great adventure but hell on a daily schedule for a kid with no discipline when it came to planning my day. The result was that too often working out went on the back burner while my appetite went unchecked.

That profile of a paunchy me set a fire in my overdeveloped belly. The next day I got up and took my Collie for a run. I had always disliked just running but it was essential for rugby and wasn't hard, just boring for me. So I put on some Converse All Stars and took off, my wonderful Levy jogging behind me as only Collies can do. At the end of the run, gasping, I looked back toward my house only a quarter of a mile away. "Yep," I told myself. "This is going to be rough." I laugh now remembering how relatively easy it was to lose my gut and get in 10k shape back then when I was in my 20s, compared to now as I head out with my new knee and hip to get my ride in with my new bicycle in my late 60s. But back then I didn't have any reference so it seemed pretty rugged.

After getting newfangled running shoes I found my feet were not so easily blistered, and reading Runner's World and writings by a fellow named George Sheehan inspired me to a great extent—so much so that I can say I actually got addicted to running. My dieting was simply eating one meal a day and getting my runs and lifts in every week.

I began keeping an exercise log, which I still do even today, except it is now in an app on my phone instead of an actual book. Keeping track of workouts just makes it easier to see improvement or decline, and to check your discipline. Remember, exercise cannot be stored, and after about 96 hours you start to detrain. Sorry. On the plus side, one of the great things about fitness is that maintaining it is easier than gaining it.

Fox and Matthews, the godfathers of interval training out of Ohio State, proved about the time I was starting to run that two intense training events a week can maintain a pretty high level of fitness. Certainly you busiest of crime fighters can work that in. So, here is the punch line of this little column; stand in front a full-length mirror and turn to the side. How is that profile? Are you happy? If not, change it. Start a fitness plan that is gradual. If every exercise bout is severe punishment it might extinguish your drive to get fit. Find a diet plan you can live with and remember that portion control costs absolutely nothing; too many plans are "get poor but not skinny" schemes that only a fifteenth-century monk could follow.

Remember this: Fitness makes you harder to kill at the cellular level, improves your attitude and emotional resilience, and just makes you look…marvelous.

Dave Smith is an internationally recognized law enforcement trainer and is the creator of "JD Buck Savage." You can follow Buck on Twitter at @thebucksavage.