頭だけで覚えた英語は忘れる
 
 
The key word in the headline is "motivates".
We can all learn, or at school level, be made to learn a Modern Foreign Language, but if our heart is not in it coupled, perhaps, with the need to learn it (e.g. a posting to the target-language country), then we won't do so successfully.

The other point to note is that having learnt the MFL, you have to maintain an interest in it and practise it regularly; otherwise it will be forgotten like so many of those subjects that we once learnt at school.

As far as English is concerned, it is in many ways the world's lingua franca.
Business people use it to communicate with others whose native language it also isn't but they use it regularly and confidently. They have to use it, so their motivation is great.
You just have to look at job advertisements in, for example, German newspapers. In them, in many jobs a good command of English is a prerequisite. ①

you have to maintain an interest in it and practise it regularly; otherwise it will be forgotten like so many of those subjects that we once learnt at school.
僕も今となっては学校で習った教科の知識はほとんど忘れた、英語、国語以外は。
国語は使っているから忘れないのは当たり前だけれども、
英語は学校でLL教室での授業があったりNHKラジオ講座を聞いていたりして、「耳」と「口」でも覚えていたからでしょうね、忘れなかったのは。

やっぱり体で覚えると忘れにくい、とは言えると思いますね。

昭和41年の「若者たち」 
♪こんなーにーしてーまでー    勉強した英語、卒業したら全部忘れちゃううんじゃ、もったいないし、割に合わないですよね。悲しく、虚しいなー、こんなにしてまでしてたら。

昨日の中国語の続き
好好学習、天天向上   毛沢東
勉強強制、卒後忘却   studyhard                      いかがでしょう? でも勉強強制しないとゆとり教育になっちゃうなー。(笑)
よく英語のテキストに
Practice makes perfect.って書いてあったような気が。