Say the compliment out loud. I have some coworkers I really dig working with. I think that every time we do projects. So SAY it.

โ€œI really enjoy working with you! We always get it done and itโ€™s always super collaborative!โ€

Donโ€™t just THINK the compliment. Say it. Then tell their boss.

@shanselman
My company has an employee recognition program that really just amounts to submitting a nomination and then the employee is included in the monthly list of "Rock Stars" along with the reason you have for nominating them. The nomination can have your name on it or be anonymous. It's not all that exciting

BUT some managers definitely include those RockStar nominations in performance reviews. So...that part makes it a good way to show appreciation.