I would like to venture out into present tense, but it is so hard for me to do. How can I work on this to be able to actually write a full book in the present tense?
Just try to write in present tense, and then when you're done with your rough draft, go back over it and fix all the places where you accidentally wrote in past tense.
Besides that: practice makes perfect.
I recently did this endeavor. I also wanted to study famous first-person present-tense narratie so I read Faulkner's "As I Lay Dying" to help.
Because past tense is the "natural" tense for stories. You're retelling events that happened, be they real or fictional. On the other hand, present tense has a sense of immediacy. Telling events as they're happening is something that only very recently has become possible (motion pictures, live news reports/livestreaming, Twitter, etc...).
A middle ground between past tense and present tense is the historical present. You're talking about past events in the present tense, which makes the narration more immersive. Try doing this: picture the story in your head as you normally would in the past tense, but then, when it comes to writing, pretend you're a historian, and write it in present tense.
Alternatively, as JRosebrookMaye, pretend you're a screenwriter. Rodriguez (a director) said that you should be able to picture the movie in your head (action, camera movement, composition, blocking, dialogue, lighting, sound...), cut by cut, before you even pick up the camera. As such, picture the story in your head, and as it materializes before your eyes, write it on the page in present tense. It should feel natural to use it since that story is happening right in front of you, at that very moment.
To answer your question, I would recommend that you envision yourself a screenwriter. In screenwriting, you have to write your story in present tense. You have to write your story in the now and in the moment. This is just how the industry works.
Try this exercise,
Imagine yourself on the computer and searching the web.
How would you write yourself searching on the web?
Would you write it like this?
"I searched the web and did some bad things."
"I am searching the web right now and doing some bad things."
The second sentence is in present tense. Did you notice it sounds more in the now? This is what you need to do.