What does resistance look and feel like?

This might be a Captain Obvious question, and that I still want to ask it. 🙂 Allowing feels like a wave that I am breathing through and observing. Not clear about resistance. The analogy of trying to push a beach ball under water makes sense, but I’m not sure how that translates. Is resistance thinking, “Nope, can’t do that” and distracting one’s self? Any example appreciated. Thank you.