You might think I'm nuts but some people really do use the gyms at hotels...I never have but there are ways to squeeze in some exercise while on vacation.
If you're going to the beach...
Take a nice 20-30 minute run/jog down the beach. Bring a yoga mat and some dummbells and leave them on the beach in front of your condo. When you get back from your run, spend another 15-20 minutes doing a few ab and arm exercises such as bicycle crunches, toe touches, pushups, tricep extensions with a dumbbell, bicep curls or really any simple stength training exercise you can do with little to no equipment.
TIP - Another great thing to do at the beach is paddle boarding. I have yet to try this but I hope one day I get to. I've heard it's a serious workout for your core and arms really your entire body! Check into renting a paddle board for the day and get to rowing.
If you're going to the country...
This one is easy, go for a hike! Before you leave do some research on any local hiking trails or state parks and plan a morning or day to visit. Hiking burns tons of calories and you don't even realize your're exercising!
If you're going to the big city...
I love going to NYC and exercising doesn't usually fit into my vacay. However, when you're in NYC all you do is WALK! Take advantage and skip the taxi or subway and spend the majority of your time walking around the city. One morning you may even take a jog or run through Central Park. What did Carrie Bradshaw always say..."Shopping is my cardio." I agree with Carrie on this one shop til your drop!
*Another great exercise while on vacation is tennis! I play regularly so I own a few racquets, but if you don't most vacation clubs will let you rent a racquet. Check out local tennis clubs or even with your condo (if you're going to the beach) they may have courts available to play. Tennis is great cardiovascular exercise and engages your whole body. It's also fun!
