If you want to train up yourself take a minute to think whether you're ruminating or problem-solving.1st you should thinking about strategies that would help you overcome an obstacle is helpful, but imagining yourself unable to tolerate pain isn't productive. Whenever you find yourself thinking about something for an extended time If you're actively solving or preventing problems, keep processing.
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There is lot of waybut, if you're simply rehashing things that already happened or making catastrophic predictions about things you can't control, change the channel. Get up and do something to get your mind off the issue and keep your brain focused on more productive activities.If you can follow this system you can train up your self that I hope.