Soldier of The Cross, Christian zeal is not to be equated with the energy of a good performer.
He who is faithful in prayer and who is completely available - that one is going to know what zeal is. He will experience this because he will see the goal clearly. God's longing will be his longing. He will be able to receive love from the Lord, and it will flow though him to others.
Zeal is not energy. Zeal is the raw life of the Lord as He is allowed to Love, through His Own.