I've personally found that my self control is significantly influenced by the amount of sleep I get. The less sleep, or lower quality sleep I get, the worse self control I have. I also find that observing (through journalling on my day) and general mindfulness of the activities I do allows me to see how I'm behaving and understanding what things I'm doing (such as wasting time on HN) is stopping me from having the discipline I want. After observation I then identify and plan ways to avoid those behaviours in the future.