If you get tired, learn to rest not quit.
Given the state of the world right now, with all the campaigning for justice and equality, it can be easy to forget to centre yourself on truth, which for me is Christ and his Gospel. A friend of mine gifted me this book a few years ago at a time when I was experiencing burnout & doubting a lot of things that I previously relied on. It's called Zeal without Burnout written by Christopher Ash.
Whether your Christian or not, this book details a few truths that all of us at some point in our lives will have to deal with. An example being coming to the realisation how important sleep & rest are and not relying on myself and ability to produce to be my source of renewal.
One thing that stuck with me after reading is that my source of rest is Christ. It also served as a reminder to be open to wise counsel through friends and family.
It's a book I would definitely recommend as it (for me) has proved useful throughout and seems it will be useful in the later years of my life.
You can pick it up here.