Like many race walkers, Philip Dunn happened upon the sport by accident. When Dunn was 10 years old he entered the Junior Olympics 1500 meter run. Later he saw on the schedule the 1500 meter race walk. Young Dunn was confused. It was the same distance he had just run; why would they be having another run? So, his dad explained and showed him what little he knew about race walking. Dunn jumped into the race and won it. As a 10 year old, he thought that was cool. Dunn was encouraged to participate in the state meet, and came in 3rd. His immediate success was not enough to pull Dunn from running, but he added race walking to his routine.
Dunn stepped up to the regional, and then eventually went to Nationals in Provo, Utah, where he finished 2nd to another walker from Oregon. In Dunn's third and fourth years at the Junior Olympics, he achieved the gold.
In 1989 Dunn graduated to the next level and competed in the Junior Nationals. His second year at the Junior Nationals he placed second behind Tim Seaman. This didn't sit well with Dunn, motivating him to push for a qualifying time for the World Junior Championships, something neither Seaman nor Dunn had accomplished previously. After a few attempts Dunn qualified for the World Juniors, walking a 44:38, well under the 45:00 time that was required. Still on a high from qualifying, He raced a few days later and set an American Junior 5K record with a time of 21:14. Dunn raced in the World Juniors in Bulgaria, finishing 16th in a field that included three future Senior world champions.
Dunn entered college in 1989 and while he never really stopped thinking about race walking, he didn't do much walking until he entered a study abroad program in Dublin, Ireland. He competed in a few races there, but his focus was on running track and cross country while in college. Dunn ran a 4:00 1500M, and was a member of a Div III cross country team that qualified for the Nationals.