My technique for finding inner peace is quite isolationist in nature. I try to avoid any form of unnecessary suffering, and learn from the lessons of sufferings that have already been in my life, to avoid them once more in the future. That way, I only suffer when suffering is inevitable, while I become wise enough to avoid suffering that isn't necessary for one's growth.
On the contrary, I optimize anything that is both healthy and reduces my levels of stress, even if it means not giving up to peer pressure and other stresses of a society that might not know me as well as myself. I carve the path in my life that brings me the calmest and the least suffering, and should I engage in an activity that is too stressful for me to endure, I 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.
We can be sure of this: a lot of what may stress us is not necessarily worth stressing over. If we rationalize the nature of the factors that cause us stress, we can use logic to reduce their dominance over us and the stress they unnecessarily cause. Let us not waste our time stressing over things that are not worth it.
Some people may criticize us for avoiding certain things that they consider important, if not vital, for human existence. However, anyone can take the opportunity to serve as an example to these people that these things are indeed not necessary. Romantic love, creating a family, and even eating meat are all considered vital by various groups of people for our prosperity and serenity. While I myself am a meat eater, I managed to live for years without meat, proving that humans are indeed capable of functioning without the consumption of meat. Keep this in mind, and you will be able to take up these sorts of challenges to show people that they are wrong, as you manage to live in serenity in the absence of these things.
Remember: things and beings that are considered critical by some—things that cause stress—can possibly be overcome. By serving as an example to the world, you will be able to both live in serenity and bring people to a stronger realization about the world and about themselves, regarding the stressful features of their lives.