Just do it consistently

Here's a good article about the benefits of exercise - giving the thumbs up for martial arts.
So, what's holding you back - what's your excuse?

Story:
You don't necessarily need to join a gym to brighten your outlook on life. In a survey of more than 1,000 adults, researchers found that people who participated in any of 22 outdoor activities (such as cycling or climbing) were happier in seven of eight categories they measured on a "Happiness Index." Participants who were inactive scored the lowest in five of those same eight categories.

Many activities may prove beneficial, but research suggests the most effective exercises are rhythmic activities that work the major muscle groups and are performed at moderate or low intensity, such as jogging, swimming, cycling and walking. Studies also have shown that mentally stimulating forms of exercise, such as martial arts, promote positive mood changes, especially as the participants' skill levels improve.

But if you're the kind of person who prefers gardening to running laps, then spending time in the garden may be your best bet. You'll reap the greatest benefits if you exercise regularly, so choose an activity you already enjoy, and find time to do it consistently.

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