As physics students, we are taught that physicists are smart, that chemists are moderately acceptable, and that biologists are certainly not very intelligent. So I wasn't inclined to take a biology course. But my father insisted, and maybe what he had in mind was that, if there were no jobs in physics, I would end up being a doctor.
I became aware of the very complex internal organization in a cell from the basic science classes, and it made me think about how all that could work. It seemed like a great mystery, especially how organelles in the cell can be arranged in three dimensions, and how thousands of proteins could find their way to the right location in the cells.