Get a fitness workout and enjoy Seafair at the same time as part of the Seafair Torchlight Run (5K and 8K). The run goes along the parade route and on the Alaskan Way Viaduct Saturday. Pirate and princess costumes are encouraged, with prizes for the best costumes and prizes for the first three finishers in each age group. Register online by 6 p.m. Thursday to get a Torchlight Run technical tee, or at the Packet Pickup party 10 a.m.-7 p.m. Friday at Green Lake Road Runner Sports. Day-of registration will be open 4-6 p.m. Saturday at Seattle Center. Proceeds benefit Ronald McDonald House Charities. The race starts at 6:30 p.m., an hour before the big parade and includes a post-race beer garden with entertainment and free food at Seattle Center; $30/advance, $35/day of event (www.seafair.com).