Manage What You Measure - [Super Simple] Health & Fitness Tip of the Day
Peter Drucker is attributed to saying that you can only manage what you can measure. In the context of food and fitness, you can't manage your progress if you aren't measuring it.
The only way to know if you're getting stronger, your body composition is changing, or you're eating better is if you track what matters. Day to day measurements don't offer much but when you have weeks worth of data you get a much clearer view of trends, what's working, and what isn't.
My biggest recommendation is to track more than just the number on the scale. Nothing exists in isolation and multiple metrics are required. In addition to weight you can track: body circumferences (arms, waist, etc.), body fat percentage, sleep (both hours slept and relative quality), reps and sets at a certain weight, and macronutrients.
The most important thing is to track what matters to you.