Hello regretful, the idea behind Mindfulness meditation is just focusing on the present. You probably know about it, and it's not easy for a lot of people. I tired it and found a way to incorporate it into my world so it works. My own version of it, what works for me. My depression is caused by anxiety, but it gets to a point where my doc wonders how the 2 are related, but seems like they are. When it was tough for me in the beginning, I used in tandem with medication (or sometimes a glass of wine) so I could get calm enough to meditate, but as I practiced and refined meditation, I slowly got off meds. I hesitated to mention the wine cause of addiction problems, so I can only say the obvious, if you're prone to addiction don't drink.
This worked for me because of traumatic past events in my life. Typical "past is depression, future is anxiety" deal.
And part of it is not to worry that you'll always be depressed, fight to get that thought out of your mind, does no good. I had the same thought. But when things got good, a little here and there, that was my hope. And I pretty much squashed that thought after I knew how it felt to be good again.
This place
https://www.headspace.com/ has some good free intros in case you haven't heard of it. Everyone need to find what works. So for for me it's meditation, 2 out of 4 T's, and 1 out of 2 P's in the past year.