We often hear and read about 'toxic negativity', but there is such a concept 'toxic positivity' as well. It is when we force ourselves and others to always look at the bright side of things ('think positive') and ignore the other sides. It can be harmful to our well-being almost as much as toxic negativity.
Positivity does not exist in a vacuum; it needs to be rooted in reality for it to be helpful. Just as we need to manage our negative feelings, but not deny them, we need to manage our positive emotions without practicing fake cheerful attitudes.
It is not easy to oscillate between the two aspects of life (positivity, negativity). In fact, it's quite a struggle, especially in old age when time, mobility, health, opportunity and everything that matters - are limited.
A positive outlook is said to help those with a major illness; it brings relief to suffering, hope to the patient. It is also believed that focusing on the positive, might help those grieving, to move on and find some solace in their loss (usually a tragic loss of a child or a young sibling).
I wouldn't really know much about that, as I turn to God and pray for help whenever I'm in distress. What helped me in the past, and helps me in the present is my belief in God and His miracles. Yes, miracles. He did some for me over the years, and I'm forever grateful to Him.