<p>I worked in orchestra management for many years, and I can echo what glassharmonica says. Most arts managers were trained as performers and retain the passion even though they may have realized their true talents were on a different branch of the artistic tree. Quite a few continue performing in one way or another.</p>
<p>Also, many music departments (and likely theater departments also) hire students to perform managerial functions. You can build up quite a resume doing student jobs.</p>