Stronger/More Intense:
* Ebullient: Overflowing with enthusiasm and excitement
* Rapturous: Feeling or expressing great pleasure or joy
* Zealous: Having or showing great energy or enthusiasm in pursuit of a cause or objective
* Ardent: Very enthusiastic or passionate
* Fervent: Having or showing great warmth or intensity of feeling
* Passionate: Having, showing, or expressing strong emotions
* Fiery: Full of passion and intensity
More Moderate:
* Keen: Eager or enthusiastic
* Excited: Feeling or showing strong and happy emotion
* Thrilled: Feeling or showing extreme excitement and pleasure
* Invigorated: Filled with energy and enthusiasm
* Animated: Lively and full of energy
* Spirited: Full of energy and enthusiasm
* Buoyant: Cheerful and optimistic
More Specific:
* Riveted: Completely engrossed in something
* Engrossed: Completely absorbed in something
* Captivated: Attracted and held the attention of someone
* Inspired: Filled with the urge or ability to create or achieve something
* Motivated: Having a strong reason to do something
* Driven: Having a strong desire to succeed
Formal:
* Eager: Having or showing a keen interest in something
* Enthusiastic: Having or showing great excitement and interest
* Passionate: Having, showing, or expressing strong emotions
* Dedicated: Devoted to a task or purpose
* Committed: Willing to give your time and effort to something
The best word to use depends on the specific context and the level of enthusiasm you want to convey.