The hardest part about starting and maintaining a meditation practice is that many people just do not want to sit still.
We are used to moving. We all have things that we need to do in our conditioned lives, and you can be sure that as soon as you sit down to meditate, a hundred other things you could be doing will pop into your head. And every one of them will seem much more important than sitting quietly for a few minutes.
No matter what position you sit in, you will get the urge to move. You might itch, or you will notice tension somewhere and you will want to shift or move. Don't worry about this too much. You aren't a bad person if you scratch or shift your legs.
You will also begin to notice how incredibly busy your mind is. You might think that it is the meditation that is causing this, but it is more likely that given the lack of other stimuli, you are just now noticing this in a way that you haven't before.
There are a few tricks to sticking with meditation. First, start slow. Don't do it so long that you want to run from the room when you're done, or else you will never do it again. Find a length of time where you feel a bit challenged, but also relaxed and refreshed when you're done. Five minutes is great. Ten or fifteen minutes might be more appropriate if you already have a yoga or martial arts practice. Like everything in meditation, it is up to you.
Another useful idea is to use some kind of support in your practice. What I mean by that is giving your mind something to do while you sit. Some might repeat a word or a mantra--"love" or "om." My favorite is counting my breaths, because I feel like I can track my progress.
Breathe in, breathe out, count one. Breathe in, breathe out, count two. Go to ten, then back to one, then back to ten. If you lose count, or if you find yourself at 37 before you notice (yes, this has happened to me), just start over.
Most of all, be kind to yourself. Days 2 through 30 are the hardest. Then it starts to become a habit.