[Beginner Question] How to set character's speed to be constant?

Good day,
I have a character that on a click rotates 90 or -90 degrees, however when he rotates his speed is 0 and than he accelerates to the walk speed, which is set, for example, to 3000. How to make him go with his speed just after the rotation?
Thanks in advance!

Clamp his movement.

Min 3000

here is a solution