However anyone that is not passionate (esp. at the start)is unlikely to last.
I was a skeptic going into Aikido with the frame of mind that "I would keep doing this until life got in the way".
What I didn't expect is that Aikido became a part of my life. It kinda snuck up on me.
I have met some very passionate beginners that disappeared after one month or less on the mat. So I don't think passion right at the start is always the sign of a committed student.