"Gratitude is not only the greatest of all virtues but the parent of all other' Cicero
The Science Bit....
We are naturally 'hard-wired' to see the negative, as our primitive ancestors needed this to spot danger and stay alive. Positive psychologists have discovered however that optimism, gratitude and focusing on our strengths can activively boost emotional wellbeing and acclaimed psychologist, Martin Seligman has repeatedly proved the benefits of these habits, with his 'what went well' and signature strengths exercises markedly lowering depression and increaing happiness levels, long after other interventions' effects had tailed off.
With daily practice we can re-train our brains to be more optimistic and reap the wellbeing rewards.