Its like a problem or an obstacle which lies in one's path
and how focused we become on that particular thing no matter
how happy or good things are. I guess this is how some lose
the point of life! They are so focused on mistakes, or a blemish
that its hard for them to look past it and move on; instead they
wither in pain and sadness.

A very good message here you have brought to the readers using
a "spot"...excellent!