A spur-of-the-moment activity is what the two of you need to get the blood moving. Spontaneous conversations about esoteric subjects work, too. Whatever it takes to get you two stimulated and off your duffs!
spur a fact or an event that makes you want to do sth better or more quickly ex. His speech was a powerful spur to action.
spontaneous(adj) 1. not planned but done because you suddenly want to do it 2. (of a person) often doing things without planning to, because they suddenly want to do them 3. done naturally, without being forced or practised
esoteric(adj) likely to be understoon or enjoyed by only a few people with a special knowledge or interest
duff (adj) unless; that does not work as it should (noun)a person's bottom