Sometimes existing shrubs on the property outgrow their space, are overshadowed by faster growing neighbors or are simply not attractive in their original location. Certainly, if you are constantly having to prune a shrub to control its growth so that it fits its space, that is an indication that it is in the wrong spot.
While there are some exceptions, most young shrubs tolerate being moved fairly well. The key to successful transplanting is to assure that the shrub has a generous rootball. When you dig it up, set the shrub on a piece of burlap and then wrap it around the rootball temporarily to hold the soil around the roots during transporting and replanting process. Keep the rootball moist and cover it with woodchips or bark mulch if there is a delay.
If a shrub is more than about 8 feet tall, it will have such a large rootball that hiring a professional arborist and his or her specialized equipment may be advisable. Follow the same procedures for timing, digging the hole and aftercare as for a newly planted balled and burlapped shrub.