正确答案：
H
解析：
根据题干信息“not advisable”可以将本题答案定位到H段“Seriously though, that is all there is to it. How long you do it each day will affect the speed of change and it’s really not advisable visualizing your success for 20 minutes per day and then spending 10 hours worrying about failing and replaying negative stuff in your head. It kind of defeats the object.”，每天视觉化你的成功20分钟，然后花10个小时用来担心失败、脑海中反复想象负面内容，这是很不明智的。故匹配段落为H。
