How do you balance adding new life experiences with maintaining a sense of simplicity?

Set up the goal always can help you

By practicing detachment.

By prioritizing what truly matters, not chasing novelty for its own sake.

Weigh pros and cons before making a decision. Take notes of lessons learnt for future.

Slow down and pay attention.

I set boundaries for most things in my life. And thankfully, now I'm mostly aware of things that might be of interest to me or, on the contrary, overwhelm me. That makes it maintaining balance a bit easier.