Adding on, "take for granted
" can also have the implied meaning of "you only know what you have when it is gone"Take
someone or something for granted
To fail to appreciate someone or something, or fail to appreciate the value of something or someone (until it's too late)
When your own children are growing up, you tend to take them for granted, and then, suddenly, they are grown up. So, don't take your child's childhood for granted, else you may regret -> You don't know what you have ( special and unique time when their children are growing up ) until they are grown up.
So you could always say "Don't take something or someone for granted" which implies that if you DO take someone or something for granted you may regret (after you've lost something or someone)
I hope that makes sense! http://idioms.thefreedictionary.com/take+for+granted