I went to university to study statistics, and I absolutely love statistics... but I was forced to learn SAS and, fucking hell, I hacked that program to shit... my presentations would have loads of pretty printing, multiple data ingest methods, proper error reporting...
So I switched into CS and liked it a lot... then I took a course on data modeling, which led to a course of Relational Algebra (essentially the abstract logical form of what you're typing in SQL to your RDBMS) then I went on to become a developer and, while I am multiskilled and able to build UIs and backends and even embedded systems... I absolutely adore data architecture and DB performance tuning.
I really can't understate how incredibly easy it is for me to look at a query over a system I understand and quickly identify likely bottlenecks and logical errors.
If you re-read my comment, you might notice there isn't a single "Eureka" moment but instead are a series of them - I think that's how most of come to be in careers we truly enjoy.