Does anyone have ideas for a client achievement gift?

I've been working with one of my clients for 3+ years and he just reached his big goal. When we started working together, he had constant pain and it was deeply affecting his mental health. We've worked together through his diagnosis, hip surgery, and so many  ups & downs. He's on vacation right now and his wife told me that he's been able to hike 4-6 miles each day with no issues!!!! 

I want to have a celebratory gift for when he's back next week. All and any ideas are greatly appreciated 🥰