We Shall All Be Changed!
1 Corinthians 15:51-52
We all like "suddenlies", and God promises that whatever remains to be accomplished in us will be done "suddenly" when Jesus returns to the earth. Until then, we can confidently trust He is working in us through His word and Spirit on a regular basis. If you are spending time in God's word and believing he is doing work in you, then you are changing from on degree of glory to another.
You do not have to be discouraged about your spiritual growth or in your walk with God, because no matter what remains to be done in the transformation of your old man into your new man, it will be finished at the appearing of Jesus in the heavenlies. If the devil tries to tell you, you are going to stay the way you are forever, he is lying. God promises in His word that He has begun a good work in you and He also will finish it (see Philippians 1:6)