I started to use emacs for the sql-oracle mode since it was tons better than the standard sqlplus client shipped by Oracle. I still kept doing most of my coding in vim but gradually was learning emacs by working with that sql mode (there is of course a mode for every database there).
Later on I started doing notes in org-mode as it was also nicer than anything else I used at that time. The ability to do ad-hoc tables/spreadsheets in it helped a lot. Then stuff just started rapidly speeding up. I found out that browsing changesets with the emacs vcs mode is great (you can open up a file in annotation mode and flip back/forward through revisions). Browsing the filesystem, grepping from withing emacs etc.
By playing around with the modes I got really used to how the editor ticks and switching to coding in it daily was just a natural evolution as I started doing more & more stuff from inside of emacs.