Here is an affordable heart rate monitor that helps you push your body the right way. The CYCPLUS Heart Rate Monitor Armband comes with Bluetooth and ANT+ connectivity. It captures your heart rate data in real-time. It is waterproof and breathable, so you can exercise with it comfortably. The battery lasts over 20 hours.
This heart rate monitor is compatible with Zwift, TrainerRoad, Ride with GPS, and other apps. You can get yours here.