The one principle behind every good program — and why a logbook, not a feeling, is how you actually apply it.
Every training program that has ever worked is built on one idea: do a little more over time than you did before. More weight, more reps, more quality sets. That is progressive overload, and it is the whole game. The problem is that "a little more" is impossible to judge from memory.
You cannot beat a number you never wrote down.
Ask yourself what you benched three weeks ago, for how many reps, and how the last set felt. If you can answer that precisely, you are rare. Most of us round up on the good days and forget the bad ones. That is exactly how plateaus hide in plain sight — you think you are pushing when you are actually repeating.
Any one of these is progress. You just need to know which lever you pulled last time — and that is a data problem, not a willpower problem.
When your last session sits right in front of you, the decision makes itself. Hit all your reps last week? Add 2.5 kg. Fell short? Repeat and win it clean this time. No spreadsheet, no math at 6am — just the previous number and a checkbox. That is the entire job of a training log, and it is why we built Bikkel around it.