There are so many ways. I'll just give an example of sleep. If you think about it, physical pain interrupts your sleep and psychological distress interrupts your sleep. When you don't sleep, you have more physical pain and you can't function.
Everything is connected. We see people sometimes self-medicating, so addictions can be related to untreated physical or mental health problems. We see all these complex interactions between every aspect of physical health and every aspect of mental health.
That's as brief as I can make it, really.