Enthusiasm
Passion, Zeal
noun, な adjective
ねっしん
決心 (けっしん) Determination, Resolution, Conviction
熱心 (ねっしん) Enthusiasm, Passion, Zeal
情熱 (じょうねつ) Passion, Enthusiasm
熱烈 (ねつれつ) Impassioned, Passionate Enthusiasm, Passionate, Vehement
Enthusiasm 熱心 is when heat 熱 stirs in your heart 心