Pray to repent

We do not have to be perfect to pray.  We do not have to be "worthy" to pray.  A lot of times we need the strength that comes through prayer to overcome sin or temptations. 
Alma 34:22-23
"Yea, cry unto him against the power of your enemies.  Yea, cry unto him against the devil, who is the enemy to all righteousness."
Doctrine and Covenants 10:5
" Pray always, that you may come off conqueror; yea that you may conquer Satan, and that you may escape the hands of the servants of Satan that do uphold his work."

It doesn't say once you have to overcome, then you can pray.  It tells us to pray TO conquer. 

An example is Alma the Younger.  He was a man that was going around destroying the church and everything surrounding it.  He was not a righteous person at all.  He was telling his son about his conversion and he stated
"...not of any worthiness of myself." Alma 36:5

That God loved him so much that even though he was doing bad things, that Alma was visited by an angel and was given guidance on how to repent and to change.  He goes on to tell his son "...teach them to withstand every temptation of the devil, WITH their faith on the Lord Jesus Christ." Alma 37:33  We are not expected to overcome sin and temptation on our own.  We will only be able to overcome all of those things WITH our faith, relying on our Savior through prayer. 

We have to remember at all times that NOTHING "shall be able to separate us from the love of God, which is in Christ Jesus our Lord."  Romans 8:39

There is nothing that is in our power to make God love us less.  He loves us eternally and infinitely and he will love us to the end and ALWAYS beckon us to return to him, no matter what we have done, what we have said, and what we have felt.  He LOVES us! 

If we ever get to a point and feel that we are not worthy to pray or shouldn't pray- remember this scripture
"Hearken unto the spirit which teacheth a man to pray ye would know that ye must pray; for the evil spirit teacheth NOT a man to pray, but teacheth him that he must not pray."  2 Nephi 32:8

If you feel that you can't pray for what ever reason.  PUSH THAT THOUGHT OUT!  That is the devil trying to get you to feel bad.  That is not what God would have you do.  He wants you to pray and feel of his love and to repent so that you can have all guilt removed.