Daily stress is generated by work most of the time, and this should be treated with the trust that heavy moments will pass. The idea is to be optimistic and have the possibility to relax by various methods in your free time, recharging yourself.
Sometimes stress comes from unexpected sources, from friends or family, from natural disasters or from death of someone you care about. Some will pass without much impact and the above will help as well. Some are making ireversible changes in your life. Dealing with things that are happening once in a lifetime are harder because your mind will come back to that event and you will never forget it. Here helps the understanding that you have to accept and learn to live with it. If you are a believer you can pray to God. You can meditate to gain a peace of mind. You can avoid thinking at it, but the thoughts about it will strike you back when you are less prepared.
A thing you should never do, don't ignore it, be conscious about stress and your brain will give you support to surpass it.