Born in Woolhope, Herefordshire, England, Tooby had her first successes in athletics in cross country running competitions. She competed at national level, winning the Welsh Cross-country Championships four times in 1984–1987 She ran at the IAAF World Cross Country Championships in 1984, finishing in 8th position overall, and improved the following year by taking sixth place at the 1985 race. She had also begun to make an impact on the track, recording the fourth fastest 5000 metres run of 1984.