Donovan grew up in Galway and took part in sports at high school, mainly being involved in Gaelic football, soccer, and rugby. However, while training for Gaelic football he found a gift for long-distance running. He made his international debut at the 1979 IAAF World Cross Country Championships staged on home soil in Limerick, running in the junior race and placing 54th. He won the intermediate section of the British Schools Cross Country International that year, as well as running in the 3000 metres heats at the 1979 European Athletics Junior Championships. His last major junior appearance was a run at the 1981 IAAF World Cross Country Championships, where he improved to 18th place and led the Irish junior team to eighth in the rankings.