I work out 5 days per week and am currently following the Jillian Michaels VIP calendar. This involves using routines from many of her DVDs with a bit of a different focus each month. The workouts span weights, HIIT, cardio, strength, yoga based, kickbox based and generally I've enjoyed the variety and am getting better results BUT... Just recently my hamstrings seem really tight making some of the routines a bit uncomfortable. Also glutes are a bit achey from time to time. I do warm up and cool down every day and wondering if anyone has any ideas why this has slowly crept up on me now. Also any idea how to resolve it ?