Self-esteem is a wonderful but delicate thing. When our self-esteem is high, we feel more resilient, we’re less vulnerable to anxiety and rejection, and less cortisol, or the stress hormone, is released into our bloodstream. The positives are obvious, but actually improving our self-esteem can be challenging, especially if we’ve experienced setbacks in the past. In a blog post on TED, psychologist Guy Winch — who has 20 years experience working with patients — explains that the problem is our self-esteem is rather unstable anyway, as it can fluctuate daily, even hourly.