The feeding and management of a blog is a commitment, just like keeping any pet.
When you own a dog, there are strategies for dealing with the days when you're too tired to walk it. Things like exhausting it fetching tennis balls, giving it one of those toys you fill with biscuits and it rolls round the yard trying to get at them, or even the ultimate laziness of a bone to chew. You can even bribe a neighbour's kid to do the walking for you.
There are similar strategies available to blog owners. The important point is to be aware that days of tiredness/distraction will strike and prepare for them. I keep a folder of "Blog Topic" bookmarks, sites that will stimulate a post or are themselves worthy of a post. A stash of your own digital photos is also handy--and remember, properly attributed, many photographers who've shared their work at places like Flickr are happy for you to blog about an image. I've noticed some bloggers share a recipe. I'm thinking of starting a tips and tricks folder--not that I have expertise on any particular subjects, but still. Reviews are also interesting and informative space fillers. And then, you can cajole guests into posting for you.
Be prepared, then blogging remains a joy and not a burden.
Also, if you know you're going to be insanely busy, simply let people know ahead of time that you'll be taking a break from blogging. No one said you had to be Super-blogger.