Why would people make themselves eunuchs "for the Kingdom of heavens sake"?

The text I'm drawing from is Matthew 19:1-12. Here is my main text: > "But he said unto them, All men cannot receive this saying, save they to whom it is given. 12 For there are some eunuchs, which were so born from their mother's womb: and there are some eunuchs, which were made eunuchs of men: **and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven's sake.** He that is able to receive it, let him receive it." (my emphasis added) Matt 19:11-12 (KJV) It would do anyone who answers well to read all of Mathew 19:1-12. Would someone please both answer the above question, and explain verses 10 and 11 in a more basic form? thanks!