Upon further thought I've decided I don't actually believe that. You're right.

I do think that's possible, but it would take more time. 10 years seems reasonable.

I don't think anyone has foomed yet because nobody has "committed themselves to this, and only this". I don't see people committed as completely to improving themselves as, say, the successful Sokushinbutsu were to mummifying themselves, or self-immolators were to burning alive.

From the page on Sokushinbutsu:

For 1,000 days (a little less than three years) the priests would eat a special diet consisting only of nuts and seeds, while taking part in a regimen of rigorous physical activity that stripped them of their body fat. They then ate only bark and roots for another thousand days and began drinking a poisonous tea made from the sap of the Urushi tree, normally used to lacquer bowls.

This caused vomiting and a rapid loss of bodily fluids, and most importantly, it made the body too poisonous to be eaten by maggots. Finally, a self-mummifying monk would lock himself in a stone tomb barely larger than his body, where he would not move from the lotus position. His only connection to the outside world was an air tube and a bell.

Each day he rang a bell to let those outside know that he was still alive. When the bell stopped ringing, the tube was removed and the tomb sealed. After the tomb was sealed, the other monks in the temple would wait another 1,000 days, and open the tomb to see if the mummification was successful.