How do I deduct stamina when spriniting

Unity Engine
1

This code is from the third person controller I have float stamina that I wanna deduct when sprinting:
also what does float targetSpeed = _input.sprint ? SprintSpeed : MoveSpeed; mean?

float targetSpeed = _input.sprint ? SprintSpeed : MoveSpeed;

            if (_input.move == Vector2.zero) targetSpeed = 0.0f;

            float currentHorizontalSpeed = new Vector3(_controller.velocity.x, 0.0f, _controller.velocity.z).magnitude;

            float speedOffset = 0.1f;
            float inputMagnitude = _input.analogMovement ? _input.move.magnitude : 1f;

            if (currentHorizontalSpeed < targetSpeed - speedOffset || currentHorizontalSpeed > targetSpeed + speedOffset)
            {
                _speed = Mathf.Lerp(currentHorizontalSpeed, targetSpeed * inputMagnitude, Time.deltaTime * SpeedChangeRate);

                _speed = Mathf.Round(_speed * 1000f) / 1000f;
            }
            else
            {
                _speed = targetSpeed;
            }
            _animationBlend = Mathf.Lerp(_animationBlend, targetSpeed, Time.deltaTime * SpeedChangeRate);

            Vector3 inputDirection = new Vector3(_input.move.x, 0.0f, _input.move.y).normalized;

            if (_input.move != Vector2.zero)
            {
                _targetRotation = Mathf.Atan2(inputDirection.x, inputDirection.z) * Mathf.Rad2Deg + _mainCamera.transform.eulerAngles.y;
                float rotation = Mathf.SmoothDampAngle(transform.eulerAngles.y, _targetRotation, ref _rotationVelocity, RotationSmoothTime);
                if (_rotateOnMove)
                {
                    transform.rotation = Quaternion.Euler(0.0f, rotation, 0.0f);
                }
            }

            Vector3 targetDirection = Quaternion.Euler(0.0f, _targetRotation, 0.0f) * Vector3.forward;

            _controller.Move(targetDirection.normalized * (_speed * Time.deltaTime) + new Vector3(0.0f, _verticalVelocity, 0.0f) * Time.deltaTime);

            if (_hasAnimator)
            {
                _animator.SetFloat(_animIDSpeed, _animationBlend);
                _animator.SetFloat(_animIDMotionSpeed, inputMagnitude);
            }
        }
2 
float targetSpeed = _input.sprint ? SprintSpeed : MoveSpeed;

// is the same as

float targetSpeed;
if(  _input.sprint)
{targetSpeed=SprintSpeed;}
else{targetSpeed=MoveSpeed;}
3

so basic

Thanks, I m struggling

 void Move()
        {
            float targetSpeed;

            if (core.stats.stamina > 10)
            {
                targetSpeed = _input.sprint ? SprintSpeed : MoveSpeed;
                if (!SceneController.tirelesModeEnabled)
                {
                    if (_input.sprint)
                    {
                        core.stats.stamina -= 15 * Time.deltaTime;
                    }
                }
            }
            else
            {
                targetSpeed = MoveSpeed;
            }

            if (_input.move == Vector2.zero) targetSpeed = 0.0f;

            float currentHorizontalSpeed = new Vector3(_controller.velocity.x, 0.0f, _controller.velocity.z).magnitude;

            float speedOffset = 0.1f;
            float inputMagnitude = _input.analogMovement ? _input.move.magnitude : 1f;

            if (currentHorizontalSpeed < targetSpeed - speedOffset || currentHorizontalSpeed > targetSpeed + speedOffset)
            {
                _speed = Mathf.Lerp(currentHorizontalSpeed, targetSpeed * inputMagnitude, Time.deltaTime * SpeedChangeRate);

                _speed = Mathf.Round(_speed * 1000f) / 1000f;
            }
            else
            {
                _speed = targetSpeed;
            }
            _animationBlend = Mathf.Lerp(_animationBlend, targetSpeed, Time.deltaTime * SpeedChangeRate);

            Vector3 inputDirection = new Vector3(_input.move.x, 0.0f, _input.move.y).normalized;

            if (_input.move != Vector2.zero)
            {
                _targetRotation = Mathf.Atan2(inputDirection.x, inputDirection.z) * Mathf.Rad2Deg + _mainCamera.transform.eulerAngles.y;
                float rotation = Mathf.SmoothDampAngle(transform.eulerAngles.y, _targetRotation, ref _rotationVelocity, RotationSmoothTime);
                if (_rotateOnMove)
                {
                    transform.rotation = Quaternion.Euler(0.0f, rotation, 0.0f);
                }
            }

            Vector3 targetDirection = Quaternion.Euler(0.0f, _targetRotation, 0.0f) * Vector3.forward;

            _controller.Move(targetDirection.normalized * (_speed * Time.deltaTime) + new Vector3(0.0f, _verticalVelocity, 0.0f) * Time.deltaTime);

            if (_hasAnimator)
            {
                _animator.SetFloat(_animIDSpeed, _animationBlend);
                _animator.SetFloat(_animIDMotionSpeed, inputMagnitude);
            }
        }

with this thou can you please help the animation is all laggy…