The overextended person may have some illness or disability that prevents them from accomplishing all that they would like. More often, the overextended person hasn't learned to just say "NO" to another term on PTA, Room Parent, overtime, carpooling, baby-sitting, cookies for the bake sale, making a "few" calls, children on three or more different traveling teams, the list goes on.
You don't have to do everything! I repeat: You don't have to do everything! There are 15 to 25 children in the class or on the team and most of the parents help out sporadically if at all. Give them something to do. Let them take your kid to practice for a change! Work does expand to fill all available time and then some-unless you stop it. If you can't say "no", try "not this time, thanks for asking." It works.
Group the tasks that you must do so you aren't running in circles. Plan home days and errand days. Make appointments in blocks so you spend all morning on the south end of town on Thursday and pick up the dry cleaning on the way home from the soccer game on Friday. Plan ahead.
Use a tool-belt style apron or one of those plastic baskets with a handle for cleaning so you can carry along all of your supplies and avoid running back and forth. Group the projects by location and supplies needed and do all related tasks at once before starting on anything else. Plan a "dirty work" day when you dress the part. Plan desk-work or something neat for the morning before going out to lunch or an appointment so you can shower and dress early and be ready to leave.
All of the above may apply sometimes. Do not feel guilty about it! All of the types are interesting, kind, fun people to know. They are not right or wrong, just different. As you learn more about yourself and how you work, use that information to create a plan that fits you. You may never be one of the spotless people, so concentrate on being the best you possible.