Updated: Aug 25, 2019
My technique to find inner peace is quite isolationist in nature - attempt to avoid unnecessary suffering - any suffering whose lesson can be taught without it - and learn from the lessons of sufferings that have already been in your life, to avoid them once more in the future. That way you will suffer only when suffering is inevitable, while you will become wise enough as to avoid suffering that isn’t necessary for one’s growth.
And on the contrary - optimize anything that is both healthy and reduces your levels of stress, even if it means not giving up to peer pressure and other stresses of a society that might not know you as well as yourself. Carve the path in your life which brings you the most calm and the least suffering, and should you engage in an activity that is too stressful for you to endure, take a break or retire from it completely if it’s not necessary.
More practical, down-to-earth activities can be recommended as well: drink a few cups of tea a day and as time goes on you will see the difference in your mood as I have seen in my own. Exercise on a regular basis to release toxic tension in your body. Stretch every now and then to relieve your bones after long times of sitting, and find time to extensively listen to music that is calm and even peaceful, to trigger in your brain the chemicals required to become more serene.
What can be assured of is this: a lot of what may stress us, isn't necessarily worth to be stressed over. Rationalize the nature of the factors of your stress, and it through logic these factors might decrease in their dominance over the stress it evitably cause us. Let us not waste our time stressing over things that aren't worth it.