It's all of the repetitive tasks that drain me. Getting breakfast once (or even twice) is fun. Making it every morning for three people is not. By the time supper rolls around, I loathe the prospect of making any more decisions: what will we eat? What nutrients have we been lacking lately? Who will eat or can eat what I have in the house? Do I have time to make X or should I go with Y? Will it make enough for leftovers? Do I start before nap time ends, or do I wait and hope they'll play and keep each other occupied? Do I need to make a run to the store before supper (please, please, please let this be "no")? Do I aim for the family to eat all together, or do I plan on the kids eating before their dad gets home so they have time to play before bedtime?
Children do not add difficulty and confusion to daily tasks; they multiply it, and multiply it on an exponential scale. Doing laundry with a toddler's "help" adds physical obstacles, interrupting questions, instruction for how they might help, un-doing of incorrectly-done "help", increased restraint in the midst of rising frustration and impatience, and a greater supply of determination to see the task through to the end. My creativity gives out after finding five different ways to say, "Please bring the toy to me." My ears are tired after hearing some rendition of, "Mommy, is that a ____?" for the twelfth time. My patience gives out after a boundary is drawn and reinforced four times in as many minutes.
Motherhood often means needing space away from your kids, but being worried about what havoc they might create in your absence. Sometimes the child can be isolated (stuck in a crib, closeted in their room with toys and a closed door) and sometimes the mom needs to be isolated (locking herself in the bathroom or out in the car, for instance). Days immediately after a vacation or a visit from grandparents or a sleepover w/ a friend will always be more draining.
The number of times you will be interrupted are proportional to the importance of the task and inversely proportional to the available timeline. --And speaking of timelines, I should peel my child away from the computer and get him some lunch (more decision-making!). It's already 2 o'clock.