grammar - What's in native speakers' mind when they use different verb forms?

My mother language doesn't have any verb forms. So if I'm going say

"This morning I ate my breakfast, then I took the bus and went to school." 

In Cantonese, I would simply say

"This morning I eat my breakfast, then I take the bus and go to school." 

The past tense is all indicated by "This morning", no changing verb forms needed.

When I am writing, I can handle tense easily, but when it comes to speaking, tense is my biggest pain.

I always use present tense for everything I say, even it's in the past. And I always forget to add "s" for the third person singular in present tense. I have to think and change the verb form in my head before I really speak. I have to go through the process like

"I take a bath"->"change take to took"->"I took a bath", or

"She get mad at me"->"change get to gets"->"She gets mad at me"

Therefore, I hesitate a lot when I speak, I know practice makes perfect, but I genuinely don't think it's all about practice, it may be about the way of how I think.

It may sound stupid, but my jaw drops a lot when I hear people speak out four or five past tense verbs in a row without hesitation. Or they always remember to conjugate for the third person singular in present tense. Let alone when they use past participle, which is even harder.

So, I hope you can really think about that, when you are speaking, what's really going on in your mind.
Do you think about the infinitive form first and then change it, or the past tense verb just pops out? Or can you explain how it works when you remember to add an "s" for present tense third person? How do you think about the act of using different verb forms? Will you instinctively sense something wrong if I use present tense to talk about something happened in the past to you?