I am smarter than average. My analytical inclination was a benefit through grade school. The other kids had to study and suffer but I was a natural and loved it.
All that came crashing down during second semester calculus at my local Junior College.
I escaped with a B, the first blemish on a soon-to-be tattered report card. The next few years were brutal as I harvested fistfuls of Cs and a few Fs.
The bloodyminded denial took a while to wear off but eventually I came to learn what the other kids knew all along; discipline works.
Due to my aptitudes I did well at the beginning and fell far behind my staid peers when the going got tough. They had years' of practice with discipline while I had to start out in the metaphorical deep end.
Discipline requires submission to a system that does not offer much in the way of flash or excitement. What it does offer is results. Being naturally inclined to a subject will give an edge at the beginning but the real rewards are found after the studied immersion that can come only with discipline.
Aptitude helps a student to start a topic. Discipline scales with the topic for as long as the student is willing to practice it.
Aptitude is nice to have but actual success hinges on discipline. Thank goodness the more valuable of the two is a choice available to everyone.