Here are a few thru-hiking resources to get you started. If you have specific questions, fire away and I will answer them to the best of my knowledge.
Guthook Guides - phone app. The 'essential' maps for most thru-hikers on most trails. They are fantastic. You can usually try the beginning section of a trail for free. This functions as GPS, showing you where the trail is, where to resupply, water sources, campsites, etc. You can also explore what trails are mapped on Guthook to see what other long-distance hikes are out there.
Allen & Mike's books (really cool backpackin' book and ultralight backpackin' book). I love these, and every time I read them I get something new out of it.
High Water River Crossings - This was useful primarily for the PCT, but also used the knowledge on the SHT, Appalachian Trail, and Wonderland Trail around Rainier.
Halfway Anywhere is someone who's humor and candor I appreciate a lot. He got me really excited for my first super-long trail (PCT). Does a great job of highlighting the 'suck' and the joy of thru-hiking.
Phil's Camino is a great short documentary about some of the gifts that come from a long-distance hike.
As for books about thru-hiking, the one that has resonated the most with me is Thirst by Heather Anish Anderson. Just an amazing f-ing book about her hike.
I have been told that Thru Hiking Will Break Your Heart by Carrot Quinn is similar in nature. Books that have not resonated so much with me are: Wild, Grandma Gatewood, A Walk in the Woods, and The Pilgrimage (Paulo Coehlo).
And the movie I've been waiting for, for what feels like an eternity, is THRU. Expected Summer 2020 but really can't come soon enough. In the meantime, I watch Mile, Mile and a Half to relive some of the beauty of the Sierra Nevada that is on the PCT/JMT. That's a good one to get you jazzed up about being in the wilderness.