When it comes to dealing with sin, we should go hard on sin, but should always be loving and compassionate towards sinners. In the same way, when it comes to health, we should go hard on unhealthy habits, but we should always be loving and compassionate towards ourselves. We all are sinful beings (I love sugar!). It's important to train our minds to do hard things. Anyone can diet and exercise, but it takes a mindset shift to make it a lasting habit. By training our minds(et) we will build the belief that we can do it, and strengthen our will to put in the hard work.