I don't love the marketing "feel" of this source but it is a good and comprehensive guide on what failure means in a lifting context: https://athleanx.com/artic

I don't love the marketing "feel" of this source but it is a good and comprehensive guide on what failure means in a lifting context: https://athleanx.com/articles/should-you-train-to-failure https://athleanx.com/articles/should-you-train-to-failure You don't "train your body to fail". You may be training bad form - and form failure is failure.