How might a strengths-based approach, like positive psychology, be more effective in working with clients suffering from mental illness?

Strength-based approaches have been shown to offer numerous advantages. Because they focus on the individual and emphasize their strength and self-determination, such approaches build on the positive attributes that are in place. Practitioners identify the resourceful and resilient dimensions of each client and assume that they retain at least some of those characteristics, even in an adverse situation. Taking this perspective is actor-centered, as the individual is the agent of change. The counselor assists the client through providing an environment conducive to the client’s control of that change. Emphasizing the individual’s emotional information-processing and thought processes facilitates communication, as individuals identify and positively value their own capacities. Rather than focus on negative factors and determine how to alter them, the counselor helps the client strengthen those attributes that are likely to effect healthy change, including their overall mindset.
Among those who can benefit are those with serious mental health issues, including depression, anxiety, and schizophrenia. Strength-based therapy is useful for developing confidence as well as reducing the stress that comes with living with their condition.
Therapy that employs a strength-based approach generally utilizes talk therapy. The client is a story-teller who recounts the stressors in their current or past life, including specific traumas. The therapist encourages identification as a survivor. Further, there is a focus on skills that have been applied to control a given situation. Identifying and emphasizing specific skills and strengths, which the client has not noticed or disregarded, encourages them to look toward continued survival and successfully dealing with difficult situations.
In addition, a strength-based counseling or therapy may be goal-oriented. The counselor may help the client identify and associate specific goals and strengths. Together, these work toward capacity building, as well as helping the client formulate expectations for themselves and others. The specific choices that each person makes build on realistic assessment of their own strengths, as well as specific, realistic expectations of what will follow.
One component is identification of resources and networks from the client’s environment that complement their individual strengths. Such resources include other individuals, groups, or associations. The counselor may aid the client in formulating ways to better utilize connections with such resources and networks. This aspect can be particular hope-inducing, as the individual considers they are not operating in isolation.
https://books.google.com/books?id=gu3V9Kys_QEC&dq=positive+psychology&lr=&as_brr=3&source=gbs_navlinks_s

https://positivepsychology.com/strengths-based-interventions/

https://www.psychologytoday.com/us/therapy-types/strength-based-therapy