Days that you are inactive come back to haunt you 7 days later when you don't receive any rewards for that day.

I find that if I have a day where I'm not inspired to produce a blog post, commenting is a good option (like the op suggests) and also using other apps helps.

There is D.Tube, Zappl, Dmania, Dlive and many other apps on the STEEM blockchain that allow you to earn.

A day spent making a couple funny memes can still be worthwhile. ;)