How to import one animation?

How to import exactly one animation from blender? I'm asking this question becouse on the internet I found only how to import animations with model, or how to import all animations that character has. I want to import one animation, becouse I want to add animations "step by step" (so when I make punching mechanic, I will make punching animation and import it, instead of making it when I did animations for walking or idle etc.). I would be very gratefu,l if you answer my question.