To start learning to tolerate conflict, first try speaking up for yourself in a situation where you would normally keep quiet. Sometimes we are so conflict adverse, we hesitate to even mention our preferences or opinions. Start challenging yourself to just speak up for yourself in little things like food or entertainment preferences. Make up an opinion if you don’t actually have one! Just learn to say what you think without being afraid of causing offense or disagreement.
Of course, the reason people hate conflict is because you can’t just say your piece and have everyone jump up and down with praise and agreement. (My preferred reaction to whatever I say!) People will push back and this is where we can lose it. But if you usually back down at this point, just take a deep breath and state your case calmly. Listen, pause to think, respond. If you are not used to conflict you will almost certainly find that you are better at dealing with it than you thought you would be. But you don’t get to peace by backing down. Be willing to walk through the discomfort of disagreement – it is your chance to learn to make peace from discord!