Depending on your level, I am assuming you are able to stand, but if not, you are still going to benefit as some of these exercises will help you in the future when you are able to stand. You are trying to develop the smaller muscles that hold your body together when making a small movement. The role of these smaller muscles is to prevent you from losing your balance. Your muscles need to get used to your body weight and the movement that accompanies it. Most exercises I perform are in my railway, which you may do without, but just be safe. I do not want you to get injured by losing your balance and falling. With each exercise be extremely cautious of your surroundings and if you fall, fall safely.

1. Stand in the railway, holding something sturdy with your hands, legs shoulder width apart.
2. Release your grip.
3. Slowly shift your weight onto the right leg, then left, feeling the weight of your body on that leg.
4. To make things more challenging, put your legs closer together as you go. You can also try putting one foot in front of the other and vice versa.

The point here is to get your muscles to learn the weight that is going to be applied. Do not worry if the narrow foot placement is exceedingly difficult, you will get it in time.