A scheduled break does not break concentration. It is the unplanned wandering off that does that, and a known break tends to replace it.

Start the movement slow enough that it is almost boring. Speed it up once it has gone smooth, and only then add the thinking part.

Slow movement practices seem to help mood, sleep and the general hum of stress. Bringing that background level down often does more for your concentration than trying to concentrate harder.

If a movement class sounds like it comes with somebody else's beliefs attached, ask what actually happens in the room before ruling it out. Much of it can be done as plain movement.