How do I learn to be consistent when I am in a hand?

[Mr. Curious]

For the most part, if I am not in a hand, I can generally read everyone else. Maybe not their specific cards, but whether they are betting with overpairs, on bluffs, making two pair, afraid of the river card, etc.

What I haven't been able to do consistently is read people like that while I am in a hand. I would say that maybe 20-30% of the time, I can be in a hand and read everyone else. There have been (a few) days when it is 100% and plenty more 0% days.

Do I just need to play more and eventually it will just "click"?
Could it be a psychological factor (fear of losing, results orientated thinking, etc.) that is taking up too much of my mental energy in a hand?
Do I just need to learn to focus on the game more?