It's only a faint glimmer on a far off horizon. You've been with the same partner forever, and you wonder what happened. You stand in the bathroom and wonder if its worth the trouble to even get something started. Arrange intimate times together, don't take them for granted.
Sexual play can start with innuendo in the morning for activity in the evening.
A lot of sexual pleasure is created by anticipation. Most of us see spontaneity go out the window when household and career responsibilities show up. As they dress for the evening, and plan their time, they allow for, and even arrange situations for sexual contact. Much early sexual contact between couples isn't spontaneous at all. Think about activities that lead to sex.