Consider using a rowing machine or a ski machine. An exercise rider is also a good choice, but it doesn't give as good a workout as a rowing or a ski machine, however, it is much easier to use. Stair-climbers, treadmills, and stationary bikes give good lower body exercise, but neglect the upper body.
Exercise seems to boost the body's natural clot busters.
There's no need to exercise daily, but be consistent at an exercise plan. The clot preventing benefits disappeared when the regular exercise program stopped. You can get the same boost with fewer calories from a piece of fruit, a cup of yogurt or a low-calorie granola bar. Your body releases additional growth hormone when you exercise aerobically. This may help slow the weakening of bones and muscles caused by the natural loss of this hormone as you age.