Character keeps tiping forward using .AddForce and Capsule Collider

Hello. I am fairly new to Unity, but I'm getting the hang of it so far!
Thing is, I am not used to using PhyX and RigidBody movement, I've been trying to use only character controllers so far, but with good results! But as you can see from the title, I have this little problem.. Here is the script that I am using to try and make my character move:

Code (CSharp):

1. public float forwardForce = 1F;
2.     Rigidbody rb;
3.     ForceMode mode = ForceMode.Force;
4.  
5.     void Start () {
6.         rb = GetComponent<Rigidbody>();
7.     }
8.  
9.  
10.     void FixedUpdate () {
11.         float h = Input.GetAxis("Horizontal");
12.         float v = Input.GetAxis ("Vertical");
13.  
14.  
15.         if (Input.GetAxis ("Vertical") > 0) {
16.             rb.AddForce(0f, 0f, 1f, mode );
17.         }
18.     }

What happens is that my character tips forward... Any help? If you need any more info, please do tell me, and I will provide it.. I'm pretty sure all of this is just some bad programming of mine lol.

 

try constraining your characters rigidbodies rotations. Its on the bottom of the rigidbody component.

 

I thought of this, but if I do so, will I be able to change those axis programmatically?

 

I believe so.