summer vacation

When it comes to seasons, I'm more of a spring and fall guy. I don't like extreme cold or heat and I'm not partial to wintery snow or summer's mosquitoes. But if you like to exercise outdoors, you really can't beat summer for its long light, consistent weather and abundance of activities.

Plus, it's the perfect season to change up your routine and work out some new muscles. Here are 5 ways to celebrate summer through exercise:

Sign up for a run ... walk or ride. Research shows that when people set a goal like taking part in an organized run, walk or bicycle ride, they stick to their exercise routine better. Although marathons are traditionally run in spring and fall, shorter runs, walks and rides abound during the summer.

Get out of the pool ... and into a lake, river or ocean. I love swimming, but I hate doing laps. I prefer swimming loops in a lake. Summer is the perfect time to move out of an indoor pool and into a body of water. Just remember swimming in open water can be more dangerous than swimming at your local pool. Be aware of your surroundings and know your limitations.

Play kickball ... or badminton. Most major cities have adult kickball leagues. You'll be surprised at how many calories a child's game can burn. Or play badminton with your family. Chasing a shuttlecock for 45 minutes will burn 230 calories.

Take a hike ... at a National Park. There are more than 360 national parks, many with easily accessible hiking trails, so chances are good you live near one. They're an inexpensive way to spend a day burning calories and enjoying natural and historical sites. You can enter any national park for free June 21, the first day of summer. Just remember to pack sunscreen and bug repellent.

Pick up a racquet ... or a baseball bat. It's no surprise that all four tennis majors take place in the summer (technically, it's summer down under when the Australian Open takes place). And you don't have to be Rafael Nadal to have a good time or burn some calories. Or join a baseball or softball league and take part in the national pastime.

As summer draws to a close, many of us will be hitting the beach for one last hurrah. If, like some members of my family, you prefer building sandcastles over swimming because the ocean seems dirty and disgusting, I have some unsettling news: The sand is even worse.

Scientists have found that levels of E. coli bacteria in sand tend to be higher than those in the water. The result, according to a recently-published study in the American Journal of Epidemiology, is that people who dig in the sand are more likely to get sick than those who take a dip in the ocean or walk on the beach.

The scientists interviewed more than 27,000 visitors at seven U.S. beaches and asked about the beachgoers' activities. Ten to 12 days later, participants were contacted by phone and asked about any illnesses they had experienced since their trip to the beach.

Those who had dug in the sand were slightly more likely to develop stomach illnesses and diarrhea than those who had not dug in the sand. The risk was further increased among people who had been buried in the sand. As you might expect, kids were especially vulnerable.

Fortunately, you don't need to forfeit that sandcastle-building contest to stay well. According to another new study, this one in the Journal of Water and Health, there's a simple solution: Wash your hands. The researchers found that subjects with sand-covered hands who rinsed in clean water removed 92% of E. coli that might otherwise have ended up in their mouths and led to illness. Rinsing four times removed virtually 100%.

Of course, it's best to use soap or an alcohol-based hand sanitizer. If you don't have access to either, though, rinsing your hands with clean water several times before you dig into your picnic basket or leave the beach can do the trick.

It's a reminder that even on vacation, Mom's advice to wash your hands still applies. To find out other surprising places where potentially harmful germs lurk and how to protect yourself, watch this video.