We cannot suffer in the past because it does not exist, what we are suffering is our memory. We cannot suffer from the future because it does not exist, what we are suffering from is our imagination. How we navigate life, how we can feel the best the most often is to be as present as we can. It is very much easier said than done, but with enough practice it is possible. Focus on our breathing, take a moment often to just be. Allow time to plan ahead, allow time to reflect. Journaling time is good for this. Wherever and whenever else, focus on the time at hand, the moment you are in now.
Is your concentration span challenging? Meditation can correct this, but ironically needs concentration to begin. Find a meditation that works for you, breathing, guided, mantra based meditations, there are many. Start with a minute, build it up over time, you can practice and develop the skill to be 15, 20 or even 30+ minutes every day.
Reduce your screen time, this constant over stimulation has damaged our attention spans. Having phone free time every day, even if just for an hour helps improve our concentration and reduce anxiety. Do more things that do not involve your phone, leave it at home. Turn off notifications, use airplane mode, put it on silent and turn it over.
When your mind wanders to the past, remind yourself that it is just a memory and bring yourself back to presence. When you mind wanders to the future, remind yourself that it is just your imagination and bring yourself back to presence. Every time we do this, the mental muscle of being present is exercised. Little by little becomes a lot. It gets easier the more we do it. Little changes of perception create big perception shifts over time. Practice it. Perception and presence.