Measurements are where any improvements start from. You cannot improve your life without having any idea about what's going wrong. You need constantly watching and inspecting your decisions, feelings and actions to grow and develop yourself.
It's similar to keeping track of the business revenue. If you are interested in developing your business you will be thoroughly monitoring your revenue every single day. You will be reviewing what's preventing you from earning more money and what's bringing them better than other things.
This strategy is perfectly applying to self-development. Summarize what you did today and what drove you. Be absolutely honest with yourself. Undertake actions to improve the situation. Get a better version of yourself tomorrow.