What helped me grow was my own drive to solve someone else's needs. Look for what it is troubles them, figure out whether and if so how software can help, and then create a tool to do so.

Yes!

One of the things that has escaped me, is how to connect diesel to a database that already exists. It is great that it can take care of creating a database and keeping it up to date, and keeps a record of all changes so you can recreate it as needed. But how does one use diesel to access a database that already got created and is in active production? A database with a structure that diesel is not allowed to alter? With pre-existing stored procedures that perform data updates?

That would be lovely!