Do you need to always watch what you're eating to live a healthy lifestyle?

Healthy Eating. You can't always eat healthy. But if you develop a pretty good eating program, you will will do well. The trick is developing the good habits so that it becomes a lifestyle change permanently. The body forgives you a few indiscretions. Just keep your basic diet healthy and you should do well!
Yes but... It is a very good idea to be very careful with what you eat. If you do so and maintain a healthy and balanced diet most of the time, the rare “misstep” will be forgiven. If not, poor eating habits will eventually cause problems. Best wishes.