Exercise does not have to be drudgery.  I enjoy the treadmill and elliptical, especially with my iPod on.  But other people prefer active hobbies, such as gardening.

Gardening uses 3-4 as much energy as just sitting around.  That means it’s an activity that uses 3-4 METS (metabolic equivalents).

From http://www.everydayhealth.com:

The advantage of gardening, in this regard, is the wide variety of activities involved each day and that these activities change with the seasons. This variation in activity is one reason gardening is a popular leisure-time undertaking for adults over the age of 65, with one 1996 publication finding 45 percent of men and 35 percent of women participating.