The four-times Olympic track champion Michael Johnson believes it's unrealistic to think athletics will ever be drug-free.
The American star of three Olympic games believes there will always be drug cheats because sport is a microcosm of real life, but he believes the Olympics and their ideals are the saving grace of athletics.
At the same time Johnson thinks his sport needs to adapt to improve its appeal.
Among his suggestions are a reassessment of track and field's events, including a shift of focus to close competition rather than world records.
