Characters are one of the most important things about a book, so it's important to connect with the people you've created in your head so they seem real to your readers.
I thought that was a good opening line *pats self on the back* so now, let's get down to it!
Basically, if you can't connect with your characters; how can you
expect your readers to? Get comfortable with them, know them, describe
them and their actions. You will need to have some sort of connection
with your characters for 2 reasons.
1) Because your book
won't reach its full potential otherwise, and 2) Because your characters
(or some of them) are going to be with you for awhile--pages and pages,
You need to know your characters. Maybe you don't have all of your characters figured out yet--their personalities, features, attitudes, etc.--but you should have your main character figured out before ever sitting down to write that first page. The main character is the "person" that is going to take you and your readers on a crazy adventure throughout the book, so you need to know who he/she is so your readers know too. They don't need to know everything at once but they need a general feel of who he/she is. You also can't have your character switching personalities every few pages (unless that's part of the plot/story, of course).
You are your characters' puppeteer. You can get them to do whatever you want! Smile, nod, shake hands, jump off a cliff--the possibilities are endless and the power is in your hands! But making your characters simply do what you want isn't enough. You need to convey/describe your character's feelings as they do that action. This will not only help you get closer to your character, but it will also make your writing better, story stronger, and give your readers necessary information.
You know that sluggish feeling you get when you know you should
probably write but don't really feel like it? We've all been there.
We've all have wanted to avoid the voices in our head at one time or
another. It's not just you. So you aren't the only one who has trouble
connecting with your characters when you force yourself to write. Forcing yourself to write can be good or bad, depending on you. Forcing yourself to write can make it difficult for you to fall into your story and connect with your characters. Maybe you should think about taking the day off from writing, even if that means putting you off-schedule. Not being able to fall into writing can be risky for your book.
Forming a relationship with your characters can be difficult, and it's probably because they're in your head, but you can get started with these tips. Good luck!
Happy writing! <3