Unfortunately, this is incorrect; zero gravity actually increases the risk of cardio-pulmonary or musculo-skeletal ailments.
For the heart, the lack of gravity means it doesn't need to work as hard. This may sound good at first, but it actually means that space is the exact opposite of a cardio workout. Due to less stress, the heartbeat slows down and the heart can actually shrink dangerously. Basically, if your heart was weak before, it's going to get much weaker in space. Studies have also shown that plasma and red blood cell counts drop in zero g, which could lead to immunology problems and anemia. And some other studies shows that radiation can cause potential long terms problems with arteries.
Without the stress of gravity, your bones also stop growing and repairing themselves. A short trip into space is basically the same as coming down with a temporary case of osteoporosis. If you already had that condition before you went up, your bones are going to get even more brittle. There's also a related problem with calcium; since you're body stops using calcium for bones, you can get a dangerous case of hypercalcemia in your blood. This can lead to kidney and heart problems. And just to round things out, the lack of pressure causes your spine and joints to expand, which can cause painful back issues and probably exacerbate arthritis.
