First thing.... The Bible don't tells the Christians to Fast!
But praying is different!
If we want to know God and want him to help us, guide us, forgive us for doing wrong and also for thanking him for existing and so on, then we need to pray.
God wants us to talk to him in prayer.
A few examples from the Bible is:1 John 5:14 :
"And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us."
The second is 1 Peter 3:12 :
"For the eyes of the Lord are upon the righteous, And his ears unto their supplication;"
In 1 Thessalonians 5:17, 18 we can read:
"pray without ceasing; in everything give thanks;"
And another one that shows us that God care, is
1 Peter 5:6,7 :
"Humble yourselfes therefore under the mighty hand of God, that he may exalt you in due time; casting all your anxiety upon him, because he careth for you."
That's what the prayers is for. God want to be our friend because he care for us.
That's why he want's us to speak to him in prayer.