How can I help friends with depression

Hi guys! My best friend has been suffering with severe depression and anxiety for the past 5 years. I’m not sure how consistent she is, but from what I know she has taken actions to improve herself (yoga, writing, prayer/ meds and therapy but not atm) but nothing seems to help. It’s getting to the point where it’s consistent, and I’m genuinely scared for her wellbeing. As someone who goes to severe depression spouts from time to time, I can’t imagine what it feels like to live like this day by day. I hate seeing her in constant pain and selfishly don’t want her to leave me. What can I do or encourage her to do.