6 Weeks of HIIT | Day 6lifeofkaizen (40)in #exercise • 7 years ago Try out this 300 rep challenge for day 6. If you're as sore as I am, it really will be a challenge, but dig deep and it'll be over before you know it. 💪 For the lunges, 1 rep = 1 on each side. #challenge #fitness #health #motivation