There are some people, who always need to do something. They can't just sit and relax. If they are on the job, they constantly try to change something (e. g. propose new approaches to existing tasks). If they go on vacation, they visit all possible places.
These people are mentally healthy, even though sometimes you may suspect them having ADHD or being in a maniac phase of manic-depressive disorder.
Note that most of the time their active nature is beneficial (stuff is get done, innovation happens), but can also have negative consequences (e. g. they may bully everyone to start a project at work, which doesn't make sense economically).
Also, they are very active not because they have to, but because it seems to be part of their nature.
What do you call such people?
In Russian there is an idiom of people having an awl in the anus (шило в попе), which makes it hard for those guys and gals to sit still. I'm looking for something similar in English.