As a professor I spend quite some time teaching students. I supervise a good number of master theses. I organize conference. I write scientific articles. I (try to) write for newspapers. I write many, many referee reports. I write recommendation letters for students. As you notice, from time to time I also write blog posts. Most of my time I spend behind a computer screen. Most of my articles see a fair amount of rejections before being accepted in journals. It is at times like these that some positive feedback really elevates the motivation. This just came in my inbox from one of my students this year:

Thank you so much for your lectures, you were such a caring, kind and good teacher to me. I wish you well for the future! 

That made me really happy. This kind of personal feedback, whether it comes from students or other researchers or just anyone out there, just puts a smile on the face. It would be great if people in general were to give treats like that more often.