You can lead a horse to water, but you can't make it drink

It means you can give someone the opportunity to learn or to do something, but you can never force him to accept that opportunity.

Eg: Greg always complains about not having enough money. I showed him an ad I saw in the newspaper for a part-time job. He said it was a good idea, but he never called the phone number. I guess you can lead a horse to water, but you can’t make it drink.

Note:

这句话的原意是你可以将马领到水前，但你无法强迫他喝水，后表示你可以给一个人学习或者做什么事情的机会，但是你无法强迫他把握住这个机会。在中国有牛不喝水莫强求的俗语，意思相近。

例：Greg总是抱怨没钱。我给他看一张报纸上的兼职广告，他说不错，可从没打过电话咨询。真是牛不喝水莫强求。