While I have not played Guandan specifically, it is a climbing game, like Big Two or Tichu, which I have. The main difference seems to be scoring by the card rank level and the wild cards.
BGG entry: https://boardgamegeek.com/boardgame/273913/guan-dan
If the leg press was good for you, then squats seem like a good option. Here’s a good place to start with lots of options for progression from whatever level you are starting from.
Every accusation a confession.
Yawara! - a judo manga / anime by Naoki Urasawa (better known for Monster and 20th Century Boys)
Earthsea by Ursula K. Leguin - in addition to interesting plots and well-developed characters, Earthsea spends a lot of time philosophizing on the conflicts that arise from human nature and how better moral systems might improve life. Lots of deep thought here.
Discworld by Terry Pratchett - another philosophizer here, but this time with humor. Most of the books stand well on their own, so don’t feel like you have to commit to a 30 book series to enjoy them.
Lord of the Rings by J. R. R. Tolkien - the standard that modern fantasy is measured by. Not much to say here that hasn’t been said before. A classic.
The Curse of Chalion by Lois McMaster Bujold - a broken man recovers himself as he investigates a mysterious threat. May appeal to Kaladin fans (Stormlight).
Stormlight Archive by Brandon Sanderson - my favorite of the Cosmere books so far. If you like Mistborn, this is the obvious follow up.
The Girl who Drank the Moon by Kelly Barnhill - Aimed at younger readers, but well-written enough for adults to enjoy as well. I love the deep care expressed by the protagonists, and how it pushes them to reexamine the assumptions they grew up with.
Digger by Ursula Vernon - a graphic novel that deservdly won the Hugo and yet hardly anyone knows about. You can even read it for free online at http://diggercomic.com/
Or Purina, for that matter?
Azul is better with 2-3 players than at 4.
Others that play well with 2 & 3 players: Dominion Race for the Galaxy Castles of Burgundy
Looks like some kind of robber fly.