Hi AlwaysAnxiety...
Are you currently taking any supplements? I do believe that a healthy diet and the right vitamins and minerals help our general sense of wellness and health a lot. Although I can't say much because I self-medicate with alcohol but am studying to become a nutritionist (makes sense? yea, didn't think so).
I sorta understand what you mean about the motivation....I am the same way. I love the gym and anything fitness related...but have a hard time 'staying on the wagon' if you will.
Have you spoken to a counsellor about how you are feeling?
There is a good book I would recommend about mental health and taking natural supplements (as you said you would prefer this over meds) called: "New Optimum Nutrition for the Mind" by Patrick Holford...worth giving it a read, maybe.

Anyways...welcome. I am new here too....but felt compelled to write. Take care.