Hi
from personal experience, I find a lot of negativity amongst people. (in fact, you can see a lot from just scanning this forum).
an important part of religious outlook, of an outlook of life, is joy. we should reject all negativity from our minds, which is ungodly.
Sikhs of old have encouraged an ethos of "Chardi Kala"- which i translate as 'the power of optimism/rising up", to *always* be in high spirits, even when faced with change, poverty, torture etc
negative thoughts and emotions are like illness- they may make a person feel dull, down, weak. optimism does the opposite.
another thing- i find that it is easy to be optimistic if i have a attitude of humility, whereas pride cause feelings of negativity.