You can lead a horse to water, but you can't make it drink is a proverb which means that you can give advice to someone and create opportunities for him but you cannot force him to make use of them.
It implies that every person usually has a mind of his own and will only do what he likes. Even favorable circumstances cannot induce a person to do something he does not want to do.
Whenever you see someone in need or distress, your first reaction is to help him and give suggestions but the person often appears to be oblivious to them.
1. Tina not only sends her son to the best school but also to a famous and reputed coaching class but he still fails to get good marks. I guess you can lead a horse to water, but you can't make it drink.
2. I gave my friend various tips on speaking English fluently but she did not pay heed to any of them. It made me realize that you can lead a horse to water, but you can't make it drink.
3. In spite of having declared a public holiday on the day of elections, very few citizens turned up to vote. We should always remember that you can lead a horse to water, but you can't make it drink.