Using these kinds of phrases makes me feel like you are telling more than showing. For instance, I don't care that your heart started to race, I care about why that's happening. I think it's because using start/realize/decide makes the action intentional instead of simply describing the action. It gives too much focus to something that should be peripheral.
Of course, in context, it might be fine. Here's an example of when it's probably suitable:
"Is this your cat?" the man asked me. My heart started to race. "Uh, no," I stuttered, backing slowly away. "I think it's ... " I pointed to the house down the street. "Jenkins." Then I turned and fled, not looking back.
In this context, the sentence helps illustrate that I am suddenly nervous or frightened. Here it is less appropriate (in my opinion):
I stretched for a few minutes then I decided to start running. My heart started to race. I realized that I had not brought my water bottle, so I decided to stop at a fountain that I knew was down the path a little farther.
In this context, this whole paragraph is giving me a step-by-step thought process. It is exceptionally boring and tedious to listen to someone's internal monologue like this. This is the essence of telling-not-showing.
You are concerned about the abruptness of the action (sometimes abrupt may be what you want though), so there are two suggestions that I would make. One is to use gerund phrases to smooth the action out:
I tossed and turned for several hours, thinking of her face. Realizing I couldn't sleep, I got up and put the kettle on.
Here, you are smoothly connecting the consequence of the realization with the action that the character took, which is what moves the plot forward. The other suggestion is to take more time to describe the important bits of the setting and movements of your characters:
We had been talking for hours. The sunlight turned golden, then narrowed through the windows on the mezzanine. She smiled at me in the dim light and took my hand. I followed her out on to the balcony as the first stars began to shine in the darkening sky.