Just wear 3D glasses..
WARNING: It’s important to state right up front, that there is a small potential risk to your health with this 3D viewing technique. The risk is very small, but I must cover myself. If you have any known problems with your eye muscles, I recommend that you do not attempt this technique. If you experience any light-headedness, headaches or other symptoms, STOP IMMEDIATELY and rest your eyes. Everyone will likely experience some slight eye fatigue when learning this technique, so it is very important to rest your eyes regularly, and only look at 3D images for short periods of time. Even once you have perfected the technique, do not over-exert your eyes. You have been warned. If you attempt to learn this technique, you agree not to hold me responsible for any ill fortune that befalls you as a result.