Our mind is a powerful thing. The thoughts we let in (positive or negative), the ideas we let in, and so on, have a major effect on our well-being. The example of the placebo effect can give us enough proof of that. Check out this article, or this article if you’re not sure what I mean, or want to dive deeper. Ultimately, what we believe in can influence our physical health. What we focus on can influence our success, our level of stress, and so on. It all comes down to mindset.