In reply to Dave Todd:
I've had a Flexispot for about 4 years and its been really good, you can source your own wood tabletop, I got mine from Etsy.
A matt to stand on is great otherwise your feet get sore.
You can Configure a schedule with the Flexispot so it automatically raises and lowers at a given time.
I personally find standing makes it hard for me to concentrate so I tend to stand on meetings/during repetitive tasks and sit when I need to think a lot.
Ball mouse has negated any wrist pain I used to get, and a good quality mechanical keyboard well help a lot. There are even ergonomic keyboards but the learning curve can be high.
I get some calf stretching done while standing.