A prescription for better health: go alfresco.  Spending time outside might have some health benefits--and the 'greening' of exercise might have some more.
D000368:Aged; D002648:Child; D015444:Exercise / Q000502:physiology* / Q000523:psychology*; D006801:Humans; D013472:Sunlight; D014807:Vitamin D / Q000378:metabolism*; D055815:Young Adult
D014807:Vitamin D