When you truly practice the Dhamma, you’re sure to get true results, i.e., happiness. If your practice isn’t true, the results won’t be true. This will lead to discouragement. Your conviction in the Buddha’s teachings will grow weak, your generosity will wither away, your precepts will be defiled and impure, and your meditation will get lazy. Eventually, you’ll blame the Buddha’s teachings, saying they’re not true, and so you’ll give up. This is the harm that comes from not acting truly.
Ajaan Lee Dhammadharo