You want to relax and enjoy travel, not to be stressed out by it. One way to do that is to ensure that you do not miss your flights by arriving at the airport too late or by forgetting necessary documents.
Almost every flight has at least one person arrive late at the boarding gate. Latecomers can cause delays for other passengers and are often not allowed to board the plane.
Bear in mind that nearly every urgent task takes about twice as long as you would reasonably expect. Looking for documents or other things that you want or need to take on your journey takes time. Stress can make people need the loo at awkward moments. Traffic tends to be heavier than expected. Remember that taxis can take far longer than expected to arrive. Finding your way to the airport by car, as well as finding your way around the airport, can also take a lot of time.
Make sure that everything you need is packed and ready on the night before your departure. Don't wait until the day of your departure to double check that your passport, tickets and health documents are readily available and valid.
Aim to arrive at the boarding gate at least an hour before necessary and you might just make it on time.
The same advice applies to train or bus journeys, although the consequences of missing them might not be as expensive or devastating.