If I were Mayor, I'd make the world a better place by
Convert all major cities to electric transport working down over twenty years starting with cities over 10M, working down to those over 1M in the first ten years, and down towards cities over 100K in the second ten years.
What/who changed my life and why
Blu Cassidy: my deceased niece. Profoundly debilitated by a metabolic disorder but managed to smile and get through to people despite the mess.