The following applies predominantly to mental pain, but the coping methods can, in some circumstances, be applied to physical pain.
Pain is Temporary.
A person living the most neglected, impoverished life, will at some point experience what it feels like to be free from pain. Pain will follow you throughout life, but at times it will lose sight of you. But, there is a distinction that must be made—the absence of pain is not synonymous with the presence of happiness. You may be stuck at work on your day off, making you unhappy, but you are not in pain, and your mood will soon change when you finish your shift. Though, if you find yourself in a much darker place, one which you will likely be stuck in for a while, there are things you can do to help cope with the pain.
These are not miracle cures for mental torment, these will not improve your mood as soon as you read them, but they might just help you get through the day.
Pain is temporary.
If you are reading this, I highly doubt it is because this is your first time experiencing pain, however it may be the first time you are experiencing pain of this magnitude. Take a few deep breaths to relax; now try to remember the last time you felt happy. This does not have to be an extended period of happiness, this can be something as simple as enjoying a takeaway, or laughing at a joke. Reminisce at this moment for as long as you would like. Note the details of the memory. Create a vivid image in your head.
Now venture back to before the happy memory—no doubt you would have been in pain at some point. This is experiential evidence that pain is temporary. The problem you have is not that you no longer feel happiness, it is that you are not as happy as you used to be, and over time this eventuates in you feeling more pain than happiness. So one key bit of advice is (to quote Zombieland) "enjoy the little things." Try to magnify any happy experiences you have by fully committing yourself to the moment. Take note of who you are with (this is important), the sounds around you, the smells, the location... Note as much as you can, as this memory is an internal pain reliever that can be revisited later.
Something else I have thought about and managed to deduce to an extent is the idea that the unavailability of exposure to prolonged happiness is the key factor in making people feel worse than they ought to. The important word being 'unavailability'. People are unhappy that they are not currently experiencing a period of prolonged happiness, but what makes people feel a hell of a lot worse, is the notion that this experience will never be an option for them.
You need to ask yourself, what were you expecting from life? It is a difficult question. Were you expecting to never feel pain again? To never face adversity? This is unrealistic. You should wake up every day expecting pain, with the mindset needed to tackle it. If you face pain that day then you are ready, but if not, then you will appreciate the day a lot more. To have this mindset you need to recognise that the problems you may face, are not always a bad thing. Overcoming challenges is what makes us human; it is how we evolve.
Start by making tasks for yourself. Small ones, that are easy to deal with. Cooking a nice meal, reading 20 pages of a book, tidying your room (I would recommend this one the most). You will begin to realise that the gratification you receive from doing such things, is a lot more meaningful than that of watching a film, drinking, or getting likes on social media.
The greatest rule I have heard for dealing with pain is taken from Jordan Peterson's 12 Rules for Life: An Antidote to Chaos...
The essence of the rule was to treat yourself as though you are one of your friends. Treat yourself in the third person. You would never tell your friend suffering from depression to suck it up, so why do it to yourself? You are worth taking care of, and if you find it too hard to talk to a friend about these things then you NEED to act as that friend for your self.
In sterquiliniis invenitur
In Filth, it will be Found.
Derived from The Alchemist, Jung offered this statement as one of comfort. I hope it may also comfort you.
To put it in its most basic form, the saying means that by suffering through hard times, you will find your character, and you will build your personality so that you can tackle anything. And only when you have been beaten down by life, and have reached your breaking point, only then will you realise what is meaningful to you. Then you take that and you pursue it to the best of your ability, and this will result in the closest thing to true happiness.
Make no mistake, life will NOT stop coming for you.
Life will NOT become any easier.
The only thing that will change is your ability to deal with life.
Pursue something that is meaningful, not something that makes you happy. Drinking alcohol makes people happy, so why not pursue that? Because it is not a long-term solution, and will only make life harder as you are always chasing a higher level of happiness than can be achieved.
My top tip for when you are down.
When I feel particularly low, I use this method to change my mood. I am not saying this will work for you, but it does for me. It is also worth noting that this method is best used sparingly, as the benefits will be more obvious to you.
Envelope your self with the imagination of the following:
You die tomorrow without warning. Brain aneurysm. You did not get a chance to say goodbye to the ones whom you called friends. You left without telling your family how much you love them. You left without rectifying wrongs or experiencing the things you wanted to.
Now, you get the chance to live on, starting from the moment you are currently in. With this second chance, imagine how much more grateful you would be for everything in your life. Imagine how you would appreciate even the simplest of things, like having dinner with the family around, looking at nature, or being with friends. Imagine how much you would want to make amends and try new things.
Imagine how differently you would conduct your life.
The sad reality is you could die tomorrow. The only difference is you get no warning, or no chance to come back. So ask your self... why don't you 'Live for Every Day'?