Appreciation is defined by Merriam Webster dictionary in three different ways firstly as a feeling of being grateful for something, secondly as an ability to understand the worth, quality, or importance of something and lastly as an ability to appreciate something
Now that we know what appreciation is, let's talk about its significance.
Remember the story of the ten lepers in the Bible
quoteLuke 17: 11. And it came to pass, as he went to Jerusalem, that he passed through the midst of Samaria and Galilee. 12. And as he entered into a certain village, there met him ten men that were lepers, which stood afar off: 13. And they lifted up their voices, and said, Jesus, Master, have mercy on us. 14. And when he saw them, he said unto them, Go shew yourselves unto the priests. And it came to pass, that, as they went, they were cleansed. 15. And one of them, when he saw that he was healed, turned back, and with a loud voice glorified God, 16. And fell down on his face at his feet, giving him thanks: and he was a Samaritan. 17. And Jesus answering said, Were there not ten cleansed? but where are the nine? 18. There are not found that returned to give glory to God, save this stranger. 19. And he said unto him, Arise, go thy way: thy faith hath made thee whole.
Ten of them were healed, only one came back to give thanks and for that act of appreciation, he was made whole meaning his limbs that were eaten by leprosy were restored, he had complete healing unlike his counterparts, there is blessing in giving thanks, don't be like the nine, always give thanks 
Have you ever gotten a gift for someone and the person just collects it and does not say thank you, does not show appreciation, how do you feel?, my guess will be as good as yours, you will be devastated, you wouldn't want to give that person anything again, so it is with God in heaven,
quotePsalm 95: 2. Let us come before his presence with thanksgiving, and make a joyful noise unto him with psalms. 3. For the LORD is a great God, and a great King above all gods.
all he asks for is our appreciation, if you refuse to thank God for the ones he has done, how do you expect to do another thing for you, for there is a saying that only a good turn deserves another, so today no matter what the circumstances you might be going through always give thanks, for every good thing come from God almighty
quote1 Thessalonians 5: 18. In every thing give thanks: for this is the will of God in Christ Jesus concerning you.
learn to always appreciate everything God has done for you, from being able to wake up in the morning and gift of air, let's be thankful, even in your place work, learn to appreciate your colleagues even if you rank higher than them,add courtesy to your lifestyle and before you know cheerfulness will be yours, you will always have joy and inner peace