You will know in all the little things that make up every day life. The language you use, the choices you make in friendships, entertainment, work, leisure activities etc. These will all come under the guiding influence of God and His word.
The choice is yours and must be made every day to maintain your commitment to God. You must pay attention to God's word, [Joshua 1:7-9]; pray [1 Thessalonians 5:7]; serve God's people [Matthew 25:34-46]; witness to His word [1 Timothy 4:2; 1 Peter 3:15]. If you do these things your life will be transformed. It will be a gradual process and you might not even be conscious of it but it will be evident to all that you have changed and are changing. [see John 3:20,21].
I hope you have found this helpful.