Michael Phelps is considered the greatest Olympian of all time. He was born in 1985 in Baltimore, Maryland and was diagnosed with ADHD as a child. He started swimming at age 7 influenced by his mother and sisters. By age 10, he held a national record for his age group. At the 2000 Olympics at age 15, he became the youngest male U.S. Olympian in 68 years. Phelps went on to win 28 medals, including 23 gold, over five Olympic games, setting numerous world records in the process. He is the most decorated Olympian of all time.