“But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to me in Jerusalem, and in all Judea and Samaria, and to the end of the earth.”
“And these signs will follow those who believe: In my name they will cast out demons; they will speak with new tongues; they will take up serpents; and if they drink anything deadly, it will by no means hurt them; they will lay hands on the sick, and they will recover.” Mark 16:17-18
“And they went out and preached everywhere, the Lord working with them and confirming the Word through the accompanying signs.” Mark 16:20
Acts 1:8 and Mark 16:17-18 are the words of Jesus. After the heart is given to God, the power of the LORD will be released into your life. With your whole heart, God will know that you can be trusted to do HIS work. Having surrendered to HIM — it then becomes a desire of your heart to please and worship HIM. Doesn’t this make you a slave? No. Doesn’t this severely restrict your happiness on earth? No. When I surrendered to God, my life and happiness exploded. No longer constrained by the fences that I built, I was free to explore the possibilities that God laid before me.
God could have manufactured some stupid robots if he wanted slaves. Instead HE gave us each a free will. The freedom to choose HIM first over earthly issues. In other words, God should have the absolute highest priority within our lives as illustrated below.