Let me summarise what I think I understand so far.
Dukha vedana (unpleasant feelings) give rise to dukkha dukkha (the suffering of suffering).
Sukha vedana (pleasant feelings) give rise to viparinama dukkha (the suffering of change), since they are subject to unexpected change while in existence, as well as subject to decay and passing away, while the sentient being who has not attained at least Arahanthood craves for it to continue indefinitely. Such a sentient being may also get bored or accustomed to the sukha vedana, and require more and more of it, or at least a different type of it to attain the same level of mundane or jhanic satisfaction.
When sentient beings strive to avoid dukha vedana and prolong sukha vedana as much as possible, they engage in sankhara dukkha (the suffering of burdensome activities). For example, they work strenuously at jobs in order to have enough money to splurge on sensual pleasures or to maintain their pride, status, power, beauty, wealth, etc. They think up elaborate plans to achieve their mundane goals such as how to obtain prestigious jobs, have a wonderful house in an esteemed neighbourhood, etc.
One question is: Do activities to maintain our health and daily lives count as sankhara dukkha? For example, is exercise to maintain our health a form of sankhara dukkha? What about brushing the teeth, showering and eating?
I understand that in order to have cooked food on our dinner tables, it is necessary to go grocery shopping, pay for the purchases, wash and cook the food, and clean up after the meals, etc. But what about the mere act of eating? There is surely effort involved, even if it is very minor.
This is for me to understand whether the Buddha Himself was subjected to sankhara dukkha. For example, when He suffered from bodily aches and pain due to previous vipaka, might he have continually changed His position or posture to lessen the pain? Would that be considered a form of sankhara dukkha?
The Buddha needed to eat to continue to live. When going round on his alms round to obtain alms food, would that be considered a form of sankhara dukkha?
Thank you very much in advance, Lal, for your answers to my question. They will be invaluable in helping me to contemplate more deeply on dukkha.