Matthew 21:18 In the morning, as Jesus was returning to Jerusalem, he was hungry, 19 and he noticed a fig tree beside the road. He went over to see if there were any figs, but there were only leaves. Then he said to it, “May you never bear fruit again!” And immediately the fig tree withered up.
20 The disciples were amazed when they saw this and asked, “How did the fig tree wither so quickly?”
21 Then Jesus told them, “I tell you the truth, if you have faith and don’t doubt, you can do things like this and much more. You can even say to this mountain, ‘May you be lifted up and thrown into the sea,’ and it will happen. 22 You can pray for anything, and if you have faith, you will receive it.”
I'm reading a book by George Muller - a man who started orphanages with a simple faith in God. He purposed that he would ask only God for things, and never man. When funds were extremely low and it was time for the 'annual report', he delayed it, because he didn't want 'man' to feel compelled to give because they learned of the need. He wanted God to always be the only One to get glory and he wanted to make sure the needs were met because of God's faithfulness. His total motivation was God's glory. I think this is what Jesus is pertaining to in the above verses.
I think the story below shows that Jesus does want us to pray specifically.
Luke 18:35 As Jesus approached Jericho, a blind beggar was sitting beside the road. 36 When he heard the noise of a crowd going past, he asked what was happening. 37 They told him that Jesus the Nazarene was going by. 38 So he began shouting, “Jesus, Son of David, have mercy on me!”
39 “Be quiet!” the people in front yelled at him.
But he only shouted louder, “Son of David, have mercy on me!”
40 When Jesus heard him, he stopped and ordered that the man be brought to him. As the man came near, Jesus asked him, 41 “What do you want me to do for you?”
“Lord,” he said, “I want to see!”
42 And Jesus said, “All right, receive your sight! Your faith has healed you.” 43 Instantly the man could see, and he followed Jesus, praising God. And all who saw it praised God, too.
When God does 'miracles' for us, it causes us to praise Him. And it causes not only us, but all who are aware of it. I was at a luncheon on Sunday and while waiting for the 'guests of honor' (friends who had moved to Oregon but were now in town), I struck up a conversation while waiting. In the course of that conversation, I told the story of how Chris and I 'came to be'. It was definately a 'God thing', and it caused us both to praise God. One of the soldiers from the Squadron we support was injured, seriously. We are praying for a miracle for him. Jesus, please heal him. We know you are able.
Although we don't know the hour when Jesus will come back for His own, again, we are told to be ready, and we are again told to die to ourselves:
John 12:23 Jesus replied, “Now the time has come for the Son of Man to enter into his glory. 24 I tell you the truth, unless a kernel of wheat is planted in the soil and dies, it remains alone. But its death will produce many new kernels—a plentiful harvest of new lives. 25 Those who love their life in this world will lose it. Those who care nothing for their life in this world will keep it for eternity. 26 Anyone who wants to be my disciple must follow me, because my servants must be where I am. And the Father will honor anyone who serves me.
27 “Now my soul is deeply troubled. Should I pray, ‘Father, save me from this hour’? But this is the very reason I came! 28 Father, bring glory to your name.”
Then a voice spoke from heaven, saying, “I have already brought glory to my name, and I will do so again.” 29 When the crowd heard the voice, some thought it was thunder, while others declared an angel had spoken to him.
30 Then Jesus told them, “The voice was for your benefit, not mine. 31 The time for judging this world has come, when Satan, the ruler of this world, will be cast out. 32 And when I am lifted up from the earth, I will draw everyone to myself.” 33 He said this to indicate how he was going to die.
34 The crowd responded, “We understood from Scripture that the Messiah would live forever. How can you say the Son of Man will die? Just who is this Son of Man, anyway?”
35 Jesus replied, “My light will shine for you just a little longer. Walk in the light while you can, so the darkness will not overtake you. Those who walk in the darkness cannot see where they are going. 36 Put your trust in the light while there is still time; then you will become children of the light.”