We're currently in the midst of the COVID-19 pandemic – the Coronavirus outbreak – and one's thoughts understandably skew darker during these uncertain times.
Though it may be challenging to achieve, Henry David Thoreau wisely counseled cultivating an optimistic outlook:
I know of no more encouraging fact than the unquestionable ability of man to elevate his life by a conscious endeavor. It is something to be able to paint a particular picture, or to carve a statue, and so to make a few objects beautiful; but it is far more glorious to carve and paint the very atmosphere and medium through which we look … To affect the quality of the day, that is the highest of arts.