In a nutshell: Would you like a $200 smartwatch for free? Mobvoi is running a promotion in which it will refund buyers the price of its TicWatch E3. The catch is that you have to be fit—and dedicated.

Anyone who buys a TicWatch E3 directly from Mobvoi’s website between July 12 and July 18 is eligible to have its entire $199 price refunded by taking part in the "21 Days Challenge." It involves completing at least 20 minutes of High Intensity Interval Training (HIIT) with an average heart rate of about 130 BMP for 21 successive days and sharing the results.

There are a few steps to the challenge, which runs until August 18. Participants must post their announcement on Twitter along with an unboxing video or pictures of the TicWatch E3, use the #hiitchallengewithTicWatchE3 hashtag, and tag three friends and @Mobvoi_Official.

Users must then share their exercise record Watermark or Chart, via the Mobvoi App, on Twitter and @Mobvoi_Official for 21 consecutive days from the date of the unboxing post. Don’t quit if you miss a day or two; you could still be eligible for a 50% or 20% partial refund. You must then DM Mobvoi’s Twitter account to verify all your check-ins and the challenge results after 21 days, before the closing date.

The challenge is open to customers in the US, UK, CA, AU, JP, SG, and EU. Full or partial refunds will be sent out within a month.

The TicWatch E3 has been praised for offering similar Snapdragon Wear 4100-powered performance as the Pro 3 model and its fitness-focused features. However, we still don’t know if it will be one of the wearables to receive the unified Wear OS update dropping later this year.