as defined:

ath·lete

/ˈaTH(ə)ˌlēt/ - noun

     a person who is proficient in sports and other forms of physical exercise.

"he had the broad-shouldered build of a natural athlete"

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pro·fi·cient

/prəˈfiSH(ə)nt/ - adjective

 

     competent or skilled in doing or using something.

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Physical exercise

     Physical activity is defined as any bodily movement produced by skeletal muscles that results in energy expenditure.

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So by definition any form of physical activity (exercise) and it in its consistency is considered to be athletic. Therefore anybody can be an athlete if they consistently do some type of physical activity. Physical activity being but not limited to basketball, running, yoga, daily stretching, and daily walks are all forms of exercise.  Staying active for at least 30 minutes with a heart rate above 110 is optimal.  A moderate intensive physical activity your heart rate should be between 64% and 76% of your maximum heart rate. You can estimate your maximum heart rate based on your age to estimate your maximum age-related heart rate subtract your age from 220.