Ready, reset, go: Our Flat-Belly Challenge has 21 days of belly-blasting workouts, tips, and recipes to help you start a new season on a fresh note. Day 13's workout is 30 minutes of cardio followed by 10 minutes of abs. Then reward yourself with a healthy dessert featuring blueberries, the power fruit that fights belly fat!

Source: POPSUGAR Photography / Ericka McConnell

30 Minutes of Cardio and 10 Minutes of Abs

Today's workout is 30 minutes of steady-state cardio followed by some serious ab work. Pick your favorite cardio — running, cycling, swimming, dancing — and keep moving at a steady pace for 30 minutes. Then strengthen your core and tone your abs with this 10-minute video featuring surprising variations of sit-ups and planks. It's perfect after a cardio session!

Paleo Blueberry Crumble

Source: POPSUGAR Photography / Lizzie Fuhr

Celebrate Summer and satisfy your sweet tooth with this grain-free crumble featuring blueberries, which studies indicate may fight belly fat. This dessert also features almonds; high in MUFAs (monounsaturated fats), almonds help burn away the fat that collects around your middle. Find the tasty recipe here.