I think cheerfulness is an under-rated virtue. To make others happy or light-hearted (which is what cheerfulness does) is indeed to strengthen them (which is what virtue does). But being cheerful is slightly different from cheerfulness itself. It implies something more lasting than a passing feeling, a transient mood; something that goes deeper than the smile on the face or the merry quip on the lips. It implies, I think, that one has acquired that stained-glass quality of letting the light shine through. To do that, one must first let the Light (note the capital letter) in. These lovely sunny days we are enjoying at the moment lift the mood but only the Light within can transform lives. Being cheerful has much to commend it.