Succulents come in many different forms and some varieties will naturally become tall as the result of healthy growth. Tall, healthy succulents tend to look full whereas stretched succulents have large gaps of stem and downturned leaves.
True stretching is a sign of etiolation, meaning that a succulent is not getting enough light. Succulents respond to light shortages by stretching to reach more sunlight. Improve light conditions by moving the plant outdoors (weather permitting), keeping it closer to a sunny window, or using a dedicated grow light on it. Stretching will not reverse, but you can prune and repot succulents to get them back into a tidy, compact form.
Please note: While it is possible to grow hardy succulents indoors, they will usually be green and slightly stretched from a lack of sunlight indoors.