Enthusiasm and excitement are like heat and a lack of enthusiasm and excitement is like cold or wet.
- I haven't got any burning interest in modern art.
- It's the hottest show in town.
- Things heated up/hotted up as soon as the music started.
- The audience was at fever pitch.
- The book was received warmly.
- He certainly has fire in his belly.
- She's always very sparky.
- They seemed very lukewarm when I mentioned it to them.
- Her response to the suggestion was tepid.
- She poured cold water on all my suggestions.
- The party turned out to be a damp squib.
- He blows hot and cold all the time, and I never know where I am with him.