I happen to just have read most of the literature on this topic. The first part of the article is well substantiated, but the second part (about training your willpower) seems to be based on very little data. So far I've been able to find only one source, I think, in Muraven/Baumeisters "Does Self-Control Resemble a Muscle?"). The title is phrased as a question for a reason. Afaik no one knows if your newly found willpower will last and if so, how long.