You have at least two choices:
- Put the Action by itself in a macro, and call that macro when needed using Execute a Macro action (KM Wiki).
- Use the excellent system by @DanThomas to save and insert Actions in a macro when needed:
- MACRO: [KMFAM] Favorite Actions and Macros
- I use this many times a day, and highly recommend it.
I actually use both methods, but use #2 the most often. It is particularly valuable for creating macro and/or Action sets as templates – which using Execute Macro is of no use.