It rather sounds as though you have little experience of people with significant MH issues, @DipsyDee .
When someone is seriously unwell, no amount of "doing something" for themself will build their confidence unless they also have access to efficient and effective therapies, professional support, appropriate medication and a supportive and understanding network of family and friends. And I can assure you that access to therapy is very, very difficult.
I've had clients who have been waiting for EMDR therapy for PTSD for several years, therapeutic counselling is limited to a fixed number of sessions, and often ends before it has achieved anything, many of my clients only see a mental health professional twice a year, and frequently not even that often. Mental health services are shockingly under-resourced, pressure on staff is considerable, and there is a high turnover of staff so even those who do get some meaningful help often have frequent changes of worker so that there is a lack of consistency in the help that they get.
CAMHS appears to be even worse than adult MH services. My friend's son (autism, C-PTSD, depression and GAD all diagnosed) waited 6 years just to be assessed. By the time he was diagnosed, he was 17, and very soon had to start all over again with adult MH services. He was out of school for most of that time.
I helped him get DLA, and then PIP when he reached 16. He uses his PIP to pay for therapy privately, and is now able to actually leave the house on his own some of the time and to get to his therapist independently. Friend is now exploring charitable funding for the EMDR therapy he should have had years ago.
If there was better access to effective support and treatment for mental health, there wouldn't be so many people dependent on state support just to stay alive.