In
Post #4 on the 4 Noble Truths, the 1st Noble Truth of Suffering is: birth, ageing, illness, death, union with what is displeasing, separation from what is pleasing, not to get what one wants, i.e. the 5 aggregates subject to clinging are suffering.
From first look, birth, ageing, illness, death, union with what is displeasing, separation from what is pleasing, not to get what one wants are suffering.
However, the crucial point is actually:
the 5 aggregates subject to clinging are suffering.
How so?
It is because we identify ourselves with the 5 aggregates (due to
ignorance, we identify ourselves with them because of wrong view -
personal identity view) that we think that (1) form is me and belongs to me, (2) feeling is me and belongs to me, (3) perception ..., (4) volitional formations ..., (5) consciousness is me and belongs to me and cling onto them (resulting from
craving and intensifies to
clinging/grasping). When things change, our so-called "self" ages/falls sick/is dying, we suffer. This kind of suffering is mental.
The awakened ones like the Buddha and the Arahants - their existential being is similarly made up of the 5 aggregates (due to old kamma), but they no longer suffer and were liberated. Because they did not identify with it and cling to it.
Reference 1:
Post #166 - clinging aggregates and sutta
Reference 2:
Post #97 - diagrammatic depiction of the 5 aggregates