You cannot just "right think" yourself 10 foot tall. But if God made you 10 foot tall, then you would know for sure you were in fact 10 foot tall because it would show, and be a reality.
You are saying that seeing is believing, which is wrong thinking. It should be the other way around. How God operates is belief first then the manifestation.
In Genesis we see this work in the creation of light, plants, animals, and man. We also see this throughout the gospels.
Matthew 21:21 "...if you have faith and do not doubt, you will not only do what was done to the fig tree, but also if you say to this mountain, 'Be removed and be cast into the sea.' It will be done."
Mark 5:34 "...Daughter, your faith has made you well. Go in peace, and be healed of your affliction."
Luke 18:42 "...Receive your sight; your faith has made you well."
John 11:40 "...Did I not say to you that if you would believe you would see the glory of God?"
Same with ceasing from sin, you cannot "right think" yourself free from sin as Joseph Prince suggests. But if Jesus Christ truly makes you free from sin, then you will in fact be free from sin, and it will show and be a reality.
You see, the key point here is that Christ has already dealt with sin when He died on the cross. You are not a slave to sin anymore because God has already bought you by the blood of Jesus. That is a fact and that is the reality.
The world works by seeing and then believing that is why God doesn't want you to be conformed to this world, but be transformed by the renewing of your mind.
John 20:29 "...Thomas, because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed."
Really good news for the true followers of Christ who see through the spirit and not through the eyes of the flesh. Praise God and our Lord Jesus Christ.