Regret and shame are natural human feelings received when one feels they've failed, but they shouldn’t be regarded as negative emotions; rather as an expansion of maturation and enlightenment.
It is when one feels regret or shame that the memory retains the best; thus, learning what shouldn’t be done again.
One should never shame their failures or hide them; rather they should explain them, without excuses, and appreciate the lesson.
It is when mistakes are transformed into lessons that we abolish shame, and, although one may still regret such actions or decisions, greater knowledge means greater opportunities to be found.
Yes, shame, regret and failures are not easy to digest. Many lose sleep over the many foolish decisions they've made, but one can decide whether to flourish their wrongs into a bush of rights and riches, or to pounder with regret and water a dead bush of past possibilities.