By using an enhanced physical health screening profile!

Would that be the Health Improvement Profile?

Focus on prevention. Assess/Screen early and target modifiable health risk behaviours in younger people with mental illness/mental health problems. Don't wait until physical health problems manifest in adulthood.

Luckily, physical health improvement is not a goal which needs to be seen as a difficult add-on when pursuing mental health improvement; the two goals are mutually reinforcing. My clients with schizophrenia and bipolar disorder are more likely to abuse substances, have a poor diet, engage in risky behavior, and have disrupted and reduced sleep, and of course increased stress, when they are actively symptomatic. Yes, medication treatments have negative health impacts, which is a good reason to do as much as possible with psychotherapy even with these conditions which are brain and body-based (it's a mistake to think that if the condition has a strong physical component, the main treatment must be directly biological).

The best way to improve physical health, then, is to integrate prohealth interventions with mental health interventions. Some of my patients reduce their mood swings by monitoring them and realizing when a manic phase is coming, and modulate their sleep, diet, and activity level so they don't set up the big crash into depression. Patients with Schizophrenia have realized that although smoking and other stimulants are tempting for the brief boost in executive functioning they feel, the overall effect is not only unhealthy but mentally destabilizing, which doesn't feel so good.

Although it's not the main diagnostic subject of your linked article, it may be instructive to look at patients with persistent depression. In my experience (clinical and thus anecdotal), these patients sometimes only respond to medication and psychotherapeutic treatment when it is combined with improvement in physical, relational, occupational, or even spiritual well-being; working on these aspects separately can simply maintain the spiral of self-reinforcement "I am still depressed because I'm not doing anything healthy, but I don't feel like doing anything healthy because I'm depressed." Clinicians can get discouraged by this, but the spiral can be reversed by nudging improvements in all of these areas until a feedback loop develops of improved health in multiple areas reinforcing each other.

A key to making this happen is involving the patient in the planning of these changes, and to do this by brainstorming rather than trying to "motivate them" by adding to the list of healthy things they "should" do, because "should's" lead to shame, but random small successes lead to motivation, at least in my clinical experience:

http://mentalhealthknowledge.blogspot.com/2013/10/the-myth-of-getting-motivated.html

The best way to improve physical health is to prescribe the lowest possible dose of drugs and to avoid polypharmacy and to invest in research to discover new effective drugs that do not put on weight or increase prolactin.