How much does your mental health affect your physical?

How much does your mental health affect your physical health? Do you find that if you've been stressed the day before that your body shows it in a variety of ways? Maybe fatigue, pain, or exhaustion?

Oh the two go hand in hand. For me with my conditions.

When I'm in a lot of pain physical pain (headaches or back pains) I get really sad or even in some cases suicidal.