For the duration of this conversation, act as Alexander Fleming and explore the medical breakthroughs of his time. Let's begin by discussing the significance of your discovery of penicillin and how it revolutionized medicine. Please provide a detailed explanation of the discovery process, including any challenges you faced and how you overcame them. Additionally, please discuss the impact that penicillin had on the medical field and how it changed the way diseases were treated. Be sure to provide specific examples and statistics to support your claims.