Stop affecting Player's velocity when colliding

I have a Runner class, which is a Cube with Rigid Body increases speed gradually with codes in Update() :

rigidbody.AddRelativeForce(new Vector3(speed, 0, 0), ForceMode.Acceleration);

When I collide with a non-rigid body (a primitive capsule), the Runner stops by the capsule. I have applied the code to destroy the capsule upon collision, but the Runner’s speed is still affected. How can the speed not to be affected by the collision? Did I need to set something on the capsule?

Set the ‘isTrigger’ flag to true on the primitive capsule and use OnTriggerEnter() to detect the collision.

Necro, but I still look for an answer. If I can’t use triggers, what I should do? Or… Ok, maybe I can calculate speeds of objects, make with them some calculations, and then just set speeds back, but this isn’t a good variant for destructible or\and fast-moving objects.
I just wanted to try to make a game with some voxel-destruction, but all my solution variants do not work as I want…