Tease your partner. Send dirty texts throughout your partner's workday, describing in detail what you'd like to do later, or whisper little things into your partner's ear while you're in public. Ramping up the sexual tension will be a great way to ensure that later, when you get the chance, you'll both be excited and enthusiastic for sex.
It takes some time for some people to get in the mood. Don't just assume your partner will be because you are. You've got to work for it and learn what your partner likes and push those buttons to get them in the mood.