"You never once hear Jesus condemning short prayers. But you do see him condemning long prayers". - Joseph Prince
He doesn't mean long prayers are bad, but unless they are from your heart, they are mindless ramblings in an effort to try to feel as though God really hears you.
Or it could even be about you praying in front of other believers at a bible study or a prayer meeting. Don't feel pressured to say all sorts of things if you don't know what to say. Just say what you want, and if they don't like how short it is, well, tough.
If they want something else said, let them say it.
Don't ever feel as though you have to make God hear you. You don't need to 'pray hard'. You can pray passionately from your heart to be sure, but making long, drawn out prayers in an effort to get God to answer you is absolutely stupid and Jesus said his Father doesn't appreciate it.
Really, guys. He isn't deaf. I'm sure his ears work a lot better than ours do.