Whether you're training for a triathlon, looking for a workout you can do indoors, or sitting at a desk all day and need to improve your posture, a few basic at-home or in-gym core workouts may be exactly what you need.
We rounded up five core-strengthening exercises on YouTube, featuring yogis, MMA fighters and more. Even if you don't have access to a gym or your own equipment, many of these exercises can be done at home -- with a little willpower. If you have a buddy to work out with, even better.
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Which core workout is most effective for you? Tell us in the comments.