Originally posted by Sorrow:

I've carved out a comfortable main base area, defeated Eikthyr and the Elder, gotten to mostly Iron Gear, and I should be ready for Bonemass after just a couple more swamp dungeons. The problem is that I'm losing motivation.

I often do "gameplay breaks". I never play the game right away as I buy it. I often give it a "taste play" for like a day or so, to then "abandon" it for weeks or even months(who am I kidding.. some games are sitting around for years). Later, I'd pick the game back up once I reach "the mood". "Taste play" is necessary for "the mood" to even appear.

Originally posted by Sorrow:

I don't know what I thought the mid-game would entail, but it seems like each biome/boss is just a repetitive grind for a few resources to get better armor or gear so you don't get one shot by the Forsaken in that area. Should I push through and try to rekindle the fire, or should I put it down for a while until I have renewed interest?

Games like Valheim are best played with long breaks, because they are satisfying your "build-loot-grind" crave. If you're not letting that crave to build up because you're playing other similar games, or is playing Valheim for too long, you might get exhausted very fast.

Originally posted by Sorrow:

Are cool things coming up next in the biome after swamp?

Yes, they are, but the gameplay process will be mostly the same. If you're looking for a DRASTIC change of actions - you ain't gonna find any.

Originally posted by Sorrow:

Give me reasons to want to keep going please.

The game imposes a very strict survival, "use all the resources you can get" focus on the gameplay. Which means you have to play slow and cautious of your decisions. If you'll just rush through the game, you might fail a bunch, drenching the last ember of interest.
If the main and basic gameplay mechanics like fighting, gathering, crafting, (re)building and discovering are irritating you and giving you no satisfaction, you'll be good just dropping the game on spot.