For some folx it means crippling inability to do the basics, for others it can be doing all the needful things but lack all joy. My favorite description comes from a teenager years ago "I has the big-sad". 

If you have the big-sad let's explore the how and why, discuss if medical interventions are something you are open to (I don't prescribe but will support your physician that does in the manner that works for you), find behavior modifications that are helpful and doable.

Regardless of how depression presents for you we will follow the rough outline of

-Figure out what depression looks like in your life and how is affecting you

-Education about how depression is a whole system issue

-Spot triggers and learn to identity them

-Find skills that will help YOU 

Again, no cookie cutter or prewritten worksheets