I often think that telemarketing and telephone sales is the best personal development training tool in the world. It teaches you to set goals which enables you to focus on getting what you want, how to handle rejection which helps with any knock backs you get in life later on, to exercise self discipline by doing the most important thing (the calls) even when you may not feel like it and to celebrate when you achieve success.
I can think of several people I worked with when working as a seminar promoter making 100 calls a day to promote Anthony Robbins and Tom Hopkins. They, like me, are all running their own successful businesses today. Making those calls was just the best training ground ever and really built our characters.