Patience requires making a decision
Patience is a quality that you can improve, starting with a conscious decision.
We don't often think about it, but each of us has a patience/impatience level. You set that level yourself, so you have the power to raise it.
Let's say you're waiting in the dentist's office. You've been to that dentist many times, so you know you'll have to wait--sometimes a half hour or more. While you may find it mildly irritating, that's just the way it is. You choose not to let yourself get upset over it, so you bring a good book and learn to appreciate the time you get to read something you enjoy.
On the way home, you get caught in a traffic jam. You've been in traffic jams before, but you don't hit one every day. You didn't expect this one. You let it upset you. By the time you get home, you've got a splitting headache.
You raised your tolerance level at the dentist's office, but you lowered it on the freeway. You didn't allow the wait at the dentist to get you shook up, but you did allow the traffic jam to get you upset. Why were you calm in one situation but not the other?
It had to do with expectations. Tolerance. You'll tolerate some irritations but not others. The key is to raise your tolerance level. It's hard, but you can do it. You've already proven that you can.
You deliberately choose not to let a situation upset you. You may not think you have that power to choose, but you do. You've proved that in the dentist's office.
Over time, you realize that you don't need to get everything you want, right now. You'd rather wait than get upset. You have to let yourself get upset. You know from experience that getting upset only hurts you, not the other person.
Once you see that you control your response to a potential irritant, you'll raise your tolerance. You're in the driver's seat, with the power to decide what's most beneficial to you.
Will you respond with your emotions or with your intellect? When you can calmly answer the question, "Is this worth getting myself upset over?", you've made a giant step toward becoming a more patient person.