Do not dwell so firmly to mistakes 
And the disappointments of the past,  
When unknown opportunities lie ahead?  
Profit by your mistakes with hope to last. 
 
Yesterday is gone - tomorrow is unknown,  
Today is the only definitive gauge 
To determine your outcome in life 
As father time turns each new page. 
 
Each forthcoming day is an empty space,  
A space that we should carefully fill 
With noble deeds and tolerable thoughts 
To conceive a worthy plan to promote good will. 
 
So don't dwell on mistakes of the past,  
Old failures and disappointments to nurture 
To constantly fill your mind with useless thoughts 
Will not aid you to seek a prosperous future.
Joseph T. Renaldi
http://www.poemhunter.com/poem/don-t-dwell-on-the-past/