The most literal meaning of effort is physical effort (think of weight lifting at the gym). The same holds true with information retention: it works best when the process of assimilating it is physically effortful.
学习要付出努力，否则只是娱乐，如果需要付出体力上的努力时，效果更好。（其实就是实践）

The fact of the matter is that digital products make it uniquely easy to trick yourself into thinking that you’re learning when you are actually being entertained.
数字产品让我们以为自己在学习，其实在娱乐。

大脑用的越多，将变的越好，这是大脑可塑性的本质。涉及到一个物质：myelin （髓磷脂）

信息获取上，区分哪些是用于学习的，哪些是娱乐。（学习收件箱）

关键，还是主动过滤，找到主题后继续深入（搜索）。