The key to staying cool, calm and collected is to have little islands in your day, regular little points of detachment from the world where you completely come away from what you are involved in. Spreading these times throughout your day when you stop and reconnect is the key to not losing your peace and fully enjoying what you are doing - whatever that may be.
How you do this is up to you. When I first started The Bright Path Ascension meditation, what was recommended was time in the morning before work, some time in the afternoon - perhaps at lunch and/or on coming home, and last thing at night.
(This is eyes closed time - "power nap" or meditation/breathing time. Anything else is fine, but time closing your eyes is much more beneficial, just so you know.)
This way I had a little "oases" (plural for oasis) so I could start the day right, plug back in so the afternoon was easier, and/or in the evening so I could let go of the day and sleep well.
It quickly made such a difference to my attitude and energy levels.
Doing this means peace is a priority to you. If you commit to these times - not let them be flexible on a if and when basis, but a definite appointment, then you are saying to yourself that remaining clear, calm and content is the most important thing.
It sets a bench mark of calm so its easier to know when you're getting wound up and you need to back down.
Without this benchmark stress just creeps up on you. Sometimes you're not aware of how uptight you're getting simply because most stress comes in little by little, a death by a thousand cuts.
When a weight gets cranked up little by little it goes un-noticed until the straw comes that breaks your back, and you yell at the person who (usually) least deserves it.
With this benchmark you are more prone to take action to stay there. You are more conscious of your physical wellbeing, your internal attitude and mood, everything.
If you're regular with a practice of stopping it means this benchmark of calm is easier to come back to. If you fly off the handle, you can let go and reset quickly. You fly off less, need to apologise less, everyone is happy.
The bottom line is the ability to act - to have clarity of choice - as opposed to reacting, habitually.
There is nothing better than the ability to consciously steer your life in the direction you wish it to go. There is no need to be captive to the ups and downs of life. You want to be captain of your own ship, and you can be, it simply requires a little practice.