When we are recipients of goodwill from others, we can feel compelled to reciprocate.
When someone generously donates their time or their experience, they have done so for their own reasons, and their value for doing so is non-monetary.
As such, a heartfelt thank-you is typically all that’s needed in return. If you’d then like to reciprocate, be sure to do so in non-monetary terms.
As soon as you say you want to pay someone for what they’ve done, the equation changes. With acts of kindness, the giver has put their heart into the gift, which means if you had to monetise the value the price could be quite high. Any money you offer would be a fraction of the all-in price. The gesture would also change the intended sentiment of the giver, as putting a price on their gift would frame it as professional and not personal.
Take for example the gift of a knitted scarf. You may receive the scarf and feel compelled to pay for the materials, but that would be a fraction of the hours of care.
You can certainly reciprocate the gesture, just don’t mix monetary and non-monetary.