Avoiding activities such as blowing the nose, exercising strenuously, and bending forward for a few days.

Then, last month, a study by Harvard University researchers concluded that only people who exercised regularly and strenuously would live longer.

Thirty years later, I understand that when you're exercising strenuously, a chemical is released in the body called endorphin, which gives you a natural high.

Only one is highly active, and it is the less active form that predominates in the young women who exercise strenuously, the researchers said.

Other critics say that even fit people risk injury if they exercise strenuously and too quickly to give form its due, as CrossFit participants often do.

But studies of young athletes exercising strenuously have suggested that in such situations protein in the muscles is broken down and converted into energy.

A typical mistake is to try to do too much at once, just as some people begin exercising too strenuously at first.

Men who exercise regularly and strenuously in their early years are less likely to develop Parkinson's disease when they are older, a new study suggests.

Based on solid evidence, exercising strenuously for more than 4 hours per week is associated with reduced breast cancer risk.

In fact, you don't have to exercise strenuously to achieve a sense of well-being and also lower the risk of heart disease.