Very few professing Christians are actively witnessing and sharing Christ with others on a regular basis. When done with the right motives, sharing Christ with others can boldly show that Christ is at the pinnacle of your life. However, when witnessing is done for the wrong reasons, out of a feeling of obligation and not joyously through repentance, rejection and hostility may be a common response to the message that you have to give.
You may be taking time to witness every week to people in your life, but still be living as a worldly, carnal individual. In the same way, you may be spending hours in prayer and Bible study every day, but still not be living for the cause of Christ.
Witnessing and evangelism must be done for the right reasons and through the right motives - Not for self gain, to appear better than others, to look like a "Good Christian", to be an example to others, to feel like you accomplished something worthwhile, to be affirmed in your salvation - No, none of these things. Witnessing must be done solely for the cause of Christ in order that God may be eternally glorified and honored through your life, death, and the age to come.
In order to witness effectively, you need to learn to rely on the power and work of the Holy Spirit, and not on your own abilities, to effectively exemplify Christ in word and action.
So, how do we become filled by the Spirit?
And how do we know when we are filled by the Spirit?