I found these words from E.M. Bounds in "The Necessity of Prayer" a good reminder, for those times when it seems too hard to obey:
"If anyone complains that man under the fall is too weak and helpless to obey these high commands of God, the answer is that, through the atonement of Christ, man IS able to obey. The atonement is God's enabling act. God works in us, through regeneration and the agency of the Holy Spirit, the enabling grace sufficient for all that is required of us under the atonement. This grace is furnished without measure in answer to prayer.
So, while God commands, He, at the same time, stands pledged to give us all the necessary strength of will and grace of soul to meet His demands. Because this is true, man has no excuse for disobedience."
So, go...don't complain, be thankful, be kind, wait on the Lord, be patient, put away bitterness, forgive, be gracious and merciful...because God gives "the enabling grace sufficient for all that is required"! Isn't that good news?