Dr. Perelman said that to his colleague, he had prepared for achieving nothing. Later, he solved in the affirmative the Poincaré conjecture.

Grigori Yakovlevich Perelman (/ˈpɛrɨlmən/perr-il-mən[dubious – discuss]; Russian: Григо́рий Я́ковлевич Перельма́н; born 13 June 1966) is a Russian mathematician who has made landmark contributions to Riemannian geometry and geometric topology. In 1994, Perelman proved the soul conjecture. In 2003, he proved Thurston’s geometrization conjecture. This consequently solved in the affirmative the Poincaré conjecture, posed in 1904, which before its solution was viewed as one of the most important and difficult open problems in topology. (wikipedia)