Bob's summer slim-down

Bob Greene is an exercise physiologist and certified personal trainer. He is also a renowned author and frequent guest on “Oprah.”

I always look forward to the summer season, particularly because it's so easy to be active when the weather is nice and the days are long. Whether you're heading to the beach for the day or simply hanging out in your own backyard, there are so many fun ways to squeeze in some exercise. And remember, the more you enjoy your exercise routine, the more likely you are to stick with it! Check out some of these ideas (my personal favorites) to get sweaty this summer:

Get wet. Working out in the water is a great option, particularly if you're recovering from certain injuries or suffer from arthritis. Swimming laps, treading water or even walking in the water provides resistance without putting much pressure on your joints. One note: Water workouts are generally less intense than other cardio activities because most of your weight is supported. You may have to go for longer and work out more intensely to get the same effects as land-based exercises. Plus, your body typically won't heat up the way it does with other types of aerobic exercise. Heating up is important because it's typically associated with a decrease in appetite; swimming, on the other hand, can actually increase your appetite. For this reason, swimming shouldn't be the only cardio activity you do if you're trying to lose weight.

Stroll in the sand. Jogging or even just walking on the beach provides a great workout. You'll burn twice as many calories on the sand as you would on the sidewalk. For a less intense workout, try walking or running on wet sand.

Pick your paddle. Outdoor rowing is a lot of work, but also a lot of fun--I frequently kayak. A rowing shell will give you the best overall workout while a kayak primarily targets your arms. The great thing is that rowing puts little stress on your joints and ligaments.

Bump, set, spike. A game of beach volleyball can be so much fun that it's easy to forget that you're getting a workout. Running and diving in the sand challenges your cardio and also helps tone and strengthen your muscles, particularly in the legs.

Spin your wheels. I'm a big fan of biking, and I have actually had the chance to ride cross-country on two occasions. In fact, they were two of my favorite life experiences. Of course, you don't have to pedal thousands of miles to reap the benefits of biking. Even if you're traveling closer to home (like to work or the grocery store) or simply to see the sites, you can still get a moderate-to-high aerobic workout. Again, because your weight is supported, you'll have to work a little longer or harder to get an intense workout. And don't forget to wear a helmet and ride carefully!

Take a hike. All you need are some good hiking shoes and a nearby trail. Check out Trails.com (www.trails.com/trails.aspx) to find one in your neighborhood) for a refreshing workout. I often go hiking when I need to unwind and de-stress.