It's never a bad time to start getting into shape. Whether you want to work off some extra holiday calories, you're trying to get ready for a summer adventure, or you just want to start feeling better every day, working out has tons of physical and mental benefits.
But whether you want to begin by training for a competitive event like a marathon or triathlon or just kick off a regular gym routine, you may run into a few surprises along the way.
Business Insider spoke with Dan Arnett, a professional triathlon coach, to see what surprises people encounter while getting into shape. Here are his top five.
SEE ALSO: An expert reveals how to train for a triathlon to get in perfect shape for spring
1. You'll gain weight.

With daily (or almost-daily) workouts, those extra pounds should just melt off, right?
Not exactly. Arnett says most people, especially men, put on some weight initially. This happens quickly too, within the first two to four weeks.
Your body adds muscle mass at the start, which makes you weigh more, even if you lose extra flab around the waist. If you've got significant weight to lose, it should come off eventually. But don't look for an immediate decrease on the scale — especially if you haven't altered your diet.
Focus on how your clothes fit instead, says Arnett.
2. If you're training for an event, you don't necessarily need a coach.

If you've signed up for a competitive event, especially something like a triathlon, you may think you need a professional coach to get you going.
But Arnett says you don't need to pay a professional if you're just getting started. Instead just create a good training plan — you can usually find one for free online.
If you want to get really serious after finishing your first few races, then you can look into a coach.
3. You still can't eat whatever you want.

It's easy to view the fact that you're burning a few hundred more calories a day as a license to indulge in all the cheeseburgers and ice cream you want.
"People expect to be able to change their diet" Arnett says.
But most of us can't eat whatever we want all the time, even if we are working out. Most people are usually are getting enough calories, so there's no need to suddenly start carb-loading.
Those training for an ultra race like an Ironman may need some additional nourishment, but they still need to eat healthy — and a person training for a first race won't get close to that level of calorie-burning.
So go ahead and enjoy the occasional cheeseburger or ice cream as you ordinarily would — but keep it occasional.
See the rest of the story at Business Insider