how to stop updating FOV

I want my fov to increase as my player sprints, but whenever i press shift to sprint it keeps updating and makes my Fov continuously updates and keeps increasing to an ungodly level, who do i make it happen only once, each time i sprint.

whole update:

void FixedUpdate()
{
    baseFov = NormalCam.fieldOfView;
    float t_hmove = Input.GetAxisRaw("Horizontal");
    float t_vmove = Input.GetAxisRaw("Vertical");

    bool sprint = Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.RightShift);

    bool IsSprinting = sprint && t_vmove > 0;

    Vector3 t_direction = new Vector3(t_vmove, 0, t_hmove);
    t_direction.Normalize();

    float t_adjustedSpeed = speed;
    if (IsSprinting) t_adjustedSpeed *= sprintModifier;

    rig.velocity = transform.TransformDirection (t_direction) * t_adjustedSpeed  * Time.deltaTime;

    if (IsSprinting) { NormalCam.fieldOfView = Mathf.Lerp(NormalCam.fieldOfView, baseFov * SprintFovModifier, Time.deltaTime * 8f); }
    else { NormalCam.fieldOfView = baseFov; }

}

just fov stuff:

    if (IsSprinting) { NormalCam.fieldOfView = Mathf.Lerp(NormalCam.fieldOfView, baseFov * SprintFovModifier, Time.deltaTime * 8f); }
    else { NormalCam.fieldOfView = baseFov; }

@heldtooth Hmm… well first question is did you assign a value to baseFov? what i mean is that you leftbaseFov as just this:

 baseFov = NormalCam.fieldOfView;

Without assigning a value to baseFov, then the fov will remain the same. May be the problem here… I am a beginner in Unity, so i am not very familiar with the code… sorry… and the text colors aren’t the colors I am familiar with, so sorry again. I hope that this will maybe help… I hope I wrote what you needed to know. Sorry once again!