As I've written before (in my primer on how to start), meditation is not a complicated thing to do, but that doesn't mean it's easy. As much as I get out of my meditation practice, I find that from time to time that I just can't seem to sit down. Even when I know I'll have a better, more relaxed day, that I will make better food choices, that I will be less likely to fly into an angry rage — still, sometimes I'm just grumpy and I don't feel like sitting down and doing it.
One of the most effective ways I've found to get around that problem is to have a number of online guided meditations at the ready. So I literally have to do less "work" to get my butt down on the floor and get into it.
Guided meditations can also help if you want to tackle a specific problem or issue, like anger, relaxation or insomnia — which is ideally practiced at night before sleep, but can be useful when one is tossing and turning too. I went through a few videos and found some that I thought worked well and were advertising-free. (While I totally understand the need to promote your classes or product, doing so at the end of a meditation video is totally inappropriate.) Bookmark this page, and maybe it will help you get into your practice when you are feeling not into it one day. Or you can search for meditations around specific issues in YouTube by typing those keywords in ('insomnia meditation' for instance).
These videos below are all 10 to 20 minutes long, and more of a general meditation, so shouldn't be too hard to fit into your day.