Misconception 1: I'm not flexible enough to meditate.
This is probably what most people think of when you say you do yoga. Well, it can be. It can be a lot 'worse' ( = difficult ) too, but yoga won't force you to do anything your body can't take. Note that this does not mean you should at least try. There are also many forms of meditation that don't require complicated poses; if you can sit down or lie down, you're all set.
Misconception 2: you need to be a member of some sect or weird cult to meditate. Wrong. Anyone can meditate. Meditation is a technique, for some a way of life, but for a normal form of meditation you don't have to join any group, wear orange robes or shave your head. Again, there are people who feel like that, but it's never a requirement.
Misconception 3: you can't be a Christian and meditate. Wrong. There are plenty of Christians who meditate. What else is prayer than a form of meditation, when you look at it from a logical point of view?
Misconception 4: when I meditate, nothing happens so I'm doing it wrong. Wrong again. When you meditate, things happen on many levels, and the levels that need most attention get that. Not always are you aware that something happens, so please don't stop but persist. At one point, and yes that can take a demotivatingly long time, you will feel something happen.