Different dropdown for the same field depending on previous answer

Hello,

In my form, I would like a dropdown to show a list depending on which answer was chosen previously. It is for a sports form, so I can explain better:

Question 1: What kind of training? Answers: Gym, Track, Field.

Question 2: What session? If Gym on 1, possible answers: Max strength, Endurance strength. If Track on 2, possible answers: Intervals, Series.

I don't want three different fields for two, but I don't see how to do it otherwise.

Any ideas?

Thanks in advance