The Word says that death and life in the power of the tongue (Proverbs 18:21). Others can speak death and life over us as well (most times not even realizing it), but the good news for those who are sons and daughters of God, the words of death are deflected because we have a shield (Ephesians 6:16). But the words of life are released into our life.
As an example, I'll share something that happened to me this afternoon.
I called my insurance to update my new address, she was telling me to do certain things that I had already done. Several times, she says to me... you're awesome.
Now some would say oh, that was nice, but she was just being polite. No, she was speaking life into me. I chose to receive those words because I am awesome and my life is awesome. I don't say that in a prideful or arrogant way; it's because of who I am in Christ, that my life is more awesome that it's ever been.
I guess that I'm saying, don't take the words of others lightly, no matter why they're speaking them or how incidental you think they may be. When others speak nice things to you, embrace them and receive them, for they will impact your life.