How can I think in principles without becoming rigid?
Thinking in principles does not mean treating context as irrelevant. It means identifying the causal relationships that make action succeed or fail. A principle is an abstract statement about how facts connect: what promotes life, trust, freedom, justice, health, training progress, honest communication, or long-range happiness. The point is to understand reality well enough that you do not have to work out every concrete case from scratch or memorize slogans.
"Rigid" can be a misleading label. It often packages together very different things: integrity, dogmatism, consistency, legalism, closed-mindedness, and loyalty to reality. Those are not the same. Refusing to reconsider a false belief is not the same as refusing to betray a true principle. Applying a rule mechanically is not the same as applying a principle consistently. The real question is not whether you are "yielding" or "unyielding". The question is unyielding about what, and why.
Good principle use is firm, but not mechanical. For example, "Keep promises." is a real principle because trust and reliability matter. But if you promised a training partner you would lift today and then developed chest pain, keeping the principle does not mean ignoring symptoms. It means respecting the value behind the promise while updating for the full context. You might say "I know I committed to training today, and I am sorry to change the plan. Chest pain is serious enough that I need to stop and get it checked. I will follow up when I know more, and I want to reschedule if I can.". That preserves integrity, health, communication, and respect.
The same applies morally. "Tell the truth." does not mean blurting private information to someone with no right to it. "Be kind." does not mean appeasing abuse. "Honor your commitments." does not mean sacrificing your health. "Respect individual rights." does not mean running a fresh economic calculation every time you wonder whether stealing a wallet might benefit you. The principle integrates the causal truth: Human beings need freedom, property, trust, and voluntary action to live and prosper.
So do not make principles compete with judgment. Judgment requires principles, whether explicit or implicit. The task is to hold true principles in a reality-oriented way: define your terms, keep the hierarchy of values clear, check the facts, and ask what the principle is actually protecting in this situation.
The practical standard is to be flexible in methods, context-sensitive in application, and open to correction in judgment. Be firm in loyalty to reality, reason, justice, and your highest values. Principles should be held firmly, not mechanically.