Optimism
The optimal state of mind is optimism. [1][2][3][4]
"My optimism wears heavy boots and is loud." -Henry Rollins
This doesn't mean unrealistic optimism, which leads to bad decision making. It is the hopeful optimism that things will continue to improve and self-correct, and people's lives will get happier, society will become more just. It is looking back on the events of your life and seeing them in the best light, where negative experiences turn into opportunities to learn, grow, or build resilience. It is the belief in an omnibenevolent universe that becomes a constant source of wonder and awe.
When you are happier, you have more motivation and energy, and you can do more to actually achieve the goals and bring about the changes you are so hopeful about. This is the type of optimism that becomes self-fulfilling.
Learning Optimism from a Book
The book by Jamil Zaki, Hope for Cynics is an excellent primer on hope, optimism, cynicism, and the effects these dispositions have on our brains. This interview on Plain English gives a good overview of the topics discussed in the book.
Stephen Pinker's The Better Angels of Our Nature is another book that makes a strong case for long-term optimism about humanity.
Automatic Optimism
The God Concept explores the how belief in omnibenevolence and the ritualized reinforcement of the goodness of the universe helps foster a lifelong sense of optimism.
Taking psychedelics has been shown to increase optimism in rats.[5] Might work for humans too.
Optimistic Trends
This infographic called The World as 100 People illustrates the long-term positive trends in society that have most contributed to greater happiness and less suffering for the greatest number of people.
No matter how bad it seems things are getting, there is no comparison with how bad things used to be. Temporary setbacks don't negate long-term progress and trends. There is every reason to be hopeful about a better future. We just need to keep at it and not give up.
Optimistic Videos
A lot of content related to optimism comes from the sales training, motivational speaking, and self-help world. This makes sense because optimism is a key factor in career success. However, this does mean that a lot of it is people trying to monetize ideas that you can easily learn for free, with a fair amount of pseudoscience and woo mixed in. While this content can be very uplifting, avoid getting grifted and move on once you hit their paywall.
The Optimists Unite subreddit is a good source of uplifting news and optimistic perspectives.
Optimistic Poetry
Derek Mahon's Kinsale really captures the vibe of optimism.
The kind of rain we knew is a thing of the past --
deep-delving, dark, deliberate you would say,
browsing on spire and bogland; but today
our sky-blue slates are steaming in the sun,
our yachts tinkling and dancing in the bay
like race-horses. We contemplate at last
shining windows, a future forbidden to no-one.
Optimistic Music
You have to admit it's getting better all the time.
Counterpoint
If you prefer to wallow in self-justified pessimism, Schopenhauer may be the philosopher for you!