Zeal is not always a feeling.
We tend to think of zeal as an energy level, stimulated by a goal. A zealot is simply someone who will not give up, and continues on. A zealot is unstoppable because of a vision of what can be, or should be, or must be.
A Soldier of The Cross is one who has made the decision to be a Living Sacrifice. That means he or she has clearly seen this world is not our home. We keep moving because we serve One who is building a Place for us, and because a supernatural transformation has taken place in us and is still taking place.
For The Soldier of The Cross, zeal is the result of a private prayer life that daily yields all to Him. Zeal is the result of dying to Self, so there can be room for the Holy Spirit to motivate us and reveal Jesus.
Zeal doesn't mean having to have thousands of people in church. Zeal can be the unpaid servant who cleans up after each meeting, who always calls on the sick, or who quietly prays about folks' troubles instead of talking about them.
Zeal means often doing what you don't feel like doing.
Ask Him to reveal this to you.
Put one foot in front of the other and keep moving. Don't look down.