You’re right: Some people aren’t all that easy to love. (They may think the same thing about us!) But Jesus’ command is clear: “Love one another. As I have loved you, so you must love one another” (John 13:34).
The key is to ask God to help you begin to look at others the same way he does. This doesn’t mean you overlook their faults or pretend they don’t exist; after all, God sees us just as we are, including our sins and our faults. He also yearns for us to get rid of them and become better people, and when we come to Christ, he puts his spirit within us to change us and help us overcome sin’s power.
But God loves us in spite of our faults. If he didn’t, he never would have sent his son into the world to give his life for our salvation. And when we begin to see people through his eyes, we’ll begin to love them the same way he does — in spite of their faults. We’ll also begin to face our own sins and shortcomings, and we’ll realize that apart from God’s grace, we aren’t any better than they are.
As you approach the holidays, ask God to give you an extra measure of patience. But most of all, ask God to help you love others the same way Christ has loved you — freely and beyond measure. It may not change them (at least at first) — but it certainly will change you.