Hi,
I read that your friend has some health issues which have led to
depression and
anxiety. In this case, this is a specific type of condition named "situational" depression and it means that the depression is a product of the chronic stressor, namely health issues.
This kind of depression is usually treated when the health issues causing the problem are resolved, relieving so the person from the chronic stress. When this is not possible, the best treatment is
psychotherapy.
If your brother/friend doesn't agree to visit a therapist, what you can do is try to be close, encourage and listen to him. You need to be very persistent but not annoying, understanding that people suffering from depression have lost interest and pleasure in their activities, but there is still hope for them. You also have to be watching out for signs of
suicide intent, as few as they may be, and contact your doctor immediately.
Hope I have answered your question. If you have any further questions I will be happy to help.
I hope your friend will get better and stronger, and you will find the strength to be persistent in helping him.
Wish you good health.