Balance, in terms of word count for individual scenes, and for main sections of a story (beginning, middle, end) was discussed here.
Balance can also be an issue when interspersing action with thought.
It’s not necessary to equalise the number of words spent on action with that spent on thought. Indeed, for a single action, it might be appopriate to follow it with much thought, before the next action.
The balance to aim for depends on what you are trying to achieve.
To check your writing, to see if you’ll need to address the balance, first identify the action/dialogue. You could embolden it. What’s left unemboldened is ‘thought’.
Look at the ratio of the number of words (or lines of text) used for both. Do you have the required mix?
Remember: no padding!