Is it in vain?

Many times the Bible commands the righteous man to rejoice. To sing and shout because the Lord knows the uprightness of their hearts and will reward them. He has said in Isaiah 45:19

"I have not spoken in secret, from somewhere in a land of darkness; I have not said to Jacob's descendants, 'Seek me in vain.' I, the LORD, speak the truth; I declare what is right"

I know in my heart that I do not seek or obey him in vain. I know that he watches over me and will repay me for every thing that I have done, or not done in obedience to him. But sometimes I am tempted to speak harshly against him or to think badly of him because I cannot see the reward or the benefit of my obedience. It seems that those who have blatantly dishonored him and sinned against him are reaping blessings while I sit in darkness. He says that is speaking harshly against him though.

Malachi 3:13-15

13 "You have said harsh things against me," says the LORD.
"Yet you ask, 'What have we said against you?'

14 "You have said, 'It is futile to serve God. What did we gain by carrying out his requirements and going about like mourners before the LORD Almighty?

15 But now we call the arrogant blessed. Certainly the evildoers prosper, and even those who challenge God escape.' "

That is so me right now. I feel as though it has all been in vain. I feel like I could cry a river. I feel like I could scream at the top of my lungs, and shake my fist at God. I feel like I could wail endlessly. When will it end? When will the pain cease? When Lord?

Psalm 51:10-12

10 Create in me a pure heart, O God,
and renew a steadfast spirit within me.

11 Do not cast me from your presence
or take your Holy Spirit from me.

12 Restore to me the joy of your salvation
and grant me a willing spirit, to sustain me.

Psalm 19:14

"May the words of my mouth and the meditation of my heart be pleasing in your sight, O LORD, my Rock and my Redeemer".