Rejoice not over me, O my enemy; when I fall, I shall rise; when I sit in darkness, the Lord will be a light to me. I will bear the indignation of the Lord because I have sinned against him, until he pleads my cause and executes judgment for me. He will bring me out to the light; I shall look upon his vindication. (Micah 7:8-9)
God loves us and forgives our sin. no matter big or small. He saved us from burnign hell and gives us eternal life with Him!! :)) never let the devil get away in telling u that u're unworthy because of ur sins/failures/etc.
if you have no reasons to praise God or worship Him, just think of the cross. of how he stretched His hands and died for us.