There are lots of challenges people do because they enjoy it. Things like trying to complete the community centre in year 1, which requires using each day to its fullest. But it's all self imposed.

There are probably only two things that could kind of be considered, which I will try to keep spoilers to a minimum for any readers but it's still a little spoilery. One is what happens at the end of year 2, but if you don't stack up then you can retrigger this on demand. And the other is the randomised quests that come late game with time limits, but this is a short term time limit (do X in X days) and you don't have to do them they are just random challenges.

Stardew is a cozy game

I must be doing something wrong then. It's one of the most stressful games I've ever played. The constant grind on the field, the need to explore and find resources to upgrade your tools, while the villagers passively-aggressively force you to interact with them and give them gifts. Then, there's a lore to uncover, but after a long day of work and responsibilities, you don't have any time or power to discover anything.

But wait, you now have the resources to largely automate the plant watering, so you might have some time to experiment with livestock. It eats grass, which there is plenty of. It'll be easy. However, just when as think you have things figured out, the winter hits, and you slowly start to realize your hay reserves will not last til spring. Shit! What would Marnie say about how I treat my animals? This is just too much...