It challenged my assumptions.

Meaning

The experience questioned or contradicted pre-conceived notions.

Examples

• John: I thought the project would be easy, but it wasn't.
• Alice: Yes, <b>it challenged my assumptions</b> too. I underestimated the complexity.
• John: Exactly! It made me rethink my approach completely.
• Alice: Me too. I learned a lot, even though <b>it challenged my assumptions</b> so much.