Don't be scared.
Don't be afraid of the instrument. It won't bite you.
Don't be afraid of making a mistake. Or having a memory lapse. Or playing in public.
Go to the hymn book. Teach yourself to play A Mighty Fortress, loudly, with great feeling, in private. Do it again. And again. LOUDER !! Do it again.
Shake your house to pieces with it finally !! Meditate on its words.
Now pick out another ringing, triumphant hymn of faith from the hymn book and do the same thing with it.
Find inspiration in the words written into these hymns, let the sound of the instrument thrill and uplift your spirit, and, I promise you, strength will come, courage will come, and your fear will be steam rollered out of existence.
Courage, strength, doesn't come from determination.
It comes from absorption of the Word of God.