Will I need to change my sinful lifestyle?

Jesus said, “If you love me, keep my commandments.”
John 14:15

The Bible says, “This is how we know that we know Him [God]: if we keep His commandments.”
1 John 2:3

The Bible says, “Even so faith, if it has no works [good deeds and righteous behavior], is dead in itself."
Apostle James 2:17

The Bible is clear on this topic. If good behavior and good deeds do not accompany your belief in Jesus, then your belief in Jesus is in vain. When you truly become a believer in Jesus, good behavior will follow your belief.

But what happens if I sin again in the future?
God has made provision to forgive all your sins. If you sin in the future, merely confess to God that you have sinned. You might say something like this to God. "I have sinned, please forgive me."