Knockback on player without having a rigidbody?

Working on a 3D game but I have a problem. I want to make my character get knockback when it collides with an object. The problem is that my character doesn't have a rigidbody. So my question is, 'How can I knock back my player without him having a rigidbody?' Without a rigidbody I can not use AddForce, so I can't figure it out. It probably won't be that complicated, but I can't figure it out. A little help would be great!