I'm writing a space game for Windows Phone in some good ol' discontinued XNA. I need the velocity of the ship to decrease gradually until it gets to zero when the user is not holding the drive button. It sounds simple but Velocity is a Vector2 and I don't know how to do this.

```
        position += velocity;
        speed = 0.04f;

        switch (driveBtn.CurrentButtonState) 
        {
            case ControlButton.ButtonState.Released:
                //Need to slow down ship when drive is not being held.
                break;

            case ControlButton.ButtonState.Pressing:
                velocity.X += (float)Math.Cos(rotation) * speed;
                velocity.Y += (float)Math.Sin(rotation) * speed;
                break;
        }

```