"Conditioned existence" refers to how things are put together — or fabricated, to use the Buddha's word — in the mind, by the mind. This is what matters, not how things arise and pass away in nature, outside of the mind. That's not a cause of suffering, but how we think about it is.
Ven. Sāriputta puts your three "types" of suffering slightly differently:
“There are these three forms of stressfulness, my friend: the
stressfulness of pain, the stressfulness of fabrication, the
stressfulness of change. These are the three forms of stressfulness.”
Sāriputta's three "forms" correspond to the three groups (delimited by semicolons) of stress described by the Buddha , except that the order changes here to change; pain; fabrication:
Birth is stressful, aging is stressful, death is stressful; sorrow,
lamentation, pain, distress, & despair are stressful; association with
the unbeloved is stressful, separation from the loved is stressful,
not getting what is wanted is stressful.
But if you think about the list enough, you may see that fabrication (the third group) points to the origination of stress, and it's also key to comprehending stress.
And comprehending stress is the first duty of the first noble truth. Once you can begin to comprehend the stress created in / by your own mind, you will become more dispassionate, more detached, and suffer less from the process.
You asked for a way to reduce stress without doing meditation, I just gave you it. But if you want to really know for yourself, you have to watch your mind creating stress — that's the main purpose of meditation.
PS. The Buddha details the stress of fabrication in his explanation of not getting what is wanted:
“And what is the stress of not getting what is wanted? In beings
subject to birth, the wish arises, ‘O, may we not be subject to birth,
and may birth not come to us.’ But this is not to be achieved by
wishing. This is the stress of not getting what is wanted. In beings
subject to aging… illness… death… sorrow, lamentation, pain, distress,
& despair, the wish arises, ‘O, may we not be subject to aging…
illness… death… sorrow, lamentation, pain, distress, & despair, and
may aging… illness… death… sorrow, lamentation, pain, distress, &
despair not come to us.’ But this is not to be achieved by wishing.
This is the stress of not getting what is wanted."