anno the very same thing has happened to me from time to time. Isn't it frustrating.
I should have been doing my pal's ironing today. I shall be doing it tomorrow instead. At the same time, I shall be in charge coping with three extremely boisterous dogs. From the moment I walk into her house, the dogs go into hyper-mode. When one barks...the rest join in. They bark at the slightest sound. They bark when one has a biscuit and the other two want it (even though they have a bowl of biscuits to squabble over.) They bark whenever the telephone rings...in fact, there is barely a quiet moment for the entire ironing session. I try to adopt a Zen-like frame of mind. 
The snow shower has been and gone and we remain free of the white stuff.
It is time for me to log off and do useful stuff aboot the hoos. My energy level is extraordinarily stagnant. Although...boast coming on...I have pedalled the exercise bike for a full twenty minutes. As I was alighting from the bike, a kind neighbour rang the doorbell and handed me a box of chocs. Oh dear! I have said to MacSporran that, instead of the usual tablet of chocolate that we treat ourselves to mid-evening we shall enjoy a chocolate from the box and most certainly not feel guilty. 