You’ve got, at the most, two months.

While those are words you never want to hear from your oncologist or cardiologist, those are the words you’ll hear from me, your de facto health-and-fitness doc, in response to one specific problem: You’ve let yourself gain weight, been neglecting your health for far too long, and are finally headed to the health club after work on Monday.

The two months I talk about begins then. But because I’m a different sort of MD, it doesn’t end with you going to the gym in The Great Beyond.

In my field of medicine, two months is about the amount of time you have to get hooked on exercise. You can talk yourself into exercising because it’s supposedly so good for you for only so long.

And then it’s so long to exercise.

So what’s your pen-and-paper MD going to suggest? That you become a type of doctor yourself. Run some tests.

Decide if the best course of treatment for you is to burn calories, train, or work out.

What I have determined after dozens of discussions with both fitness flunkies and fanatics is your type of exercise has to be consistent with your goals — which are really just a reflection of your personality — to work over the long term.

Find a match and you’ll create a way of life that leads to optimal health.

For instance, one 60-plus cyclist I know who can still keep pace with riders in their 20s and 30s was the epitome of a couch potato as a kid. When I asked him what he later did in high school, he said, “Threw a little Frisbee. Smoked a lot of dope.”

But once he rode a bike on the track at the velodrome, he got hooked on something else. Forty years later, he’s still a cycling junkie and looking far more like he’s 44 than 64.

Conversely, I knew a guy who told me that no matter, every time he started running he would give up after about two months’ time. When he asked me what he should do, I said, “Try something else.”

He’s a linebacker-sized guy who carries mostly fast-twitch muscles, the sort needed to sprint but go unused when you go for a jog. So not only is he a slow runner because of his size and muscle fiber type, but he’s also hurt all the time from the pounding his feet and legs take because of both.

The last time I saw him, he had taken my advice and taken advantage of all those fast-twitch muscles. He had been doing Cross Fit workouts for five years and loving them.

Which brings us back to the decision you need to make if you’ve been away from exercise and want to get back to it: Do you burn cals, train, or work out?

While the choices may strike you as being the same, here’s the distinction I make.

Those whose goal it is too simply burn cals, have no great emotional stake in the workout. They view exercise the way a fitness fanatic might view flossing his teeth: perfunctorily, as something that just needs to be done.

In this case, exercise variety is essential. If Monday’s workout is aerobic, Tuesday’s should feature lifting weights. If Monday’s workout used the elliptical trainer, Thursday’s should feature the rowing machine.

Or better yet, be any type that can be done outside.

What cal burners don’t want to change is that daily (or nearly daily) expenditure of calories because their goal is to keep the body in good working order by working it regularly.

Those who work out want to do a bit more than burn cals. They want not only to engender good health but to also test themselves in some way.

Keeping a steady pace on a treadmill for 30 minutes four times a week isn’t a true test and would sap their desire to exercise over time. They need to push themselves into uncharted territory, see if they can do a little bit more than the workout before, or their workout buddy.

Part of the allure for those who work out is learning about themselves. Part of the allure for those who train is learning how they handle competition.

For exercisers who train, getting better at a specific sport is the golden goal. Therefore, they can mentally allow themselves to take an easy day and look like a cal burner for a day after two intense workouts in a row because they know it’s needed for long-term improvment.

They also can summon up the motivation to take themselves to the absolute limit even though they were just there with that last all-out interval two minutes ago.

To do that, survive, and then see that pay dividends in a race or a competition is what makes them feel alive.

And keeps them coming back for more.

But you don’t have to be this hard core to want to come back for more.

You just have to understand yourself, recognize your goals, and then experiment until you find a form of exercise and an exercise routine that fits both.