Our thoughts influence our emotions and our emotions drive our actions.
This truth is easy to grasp in your own life: change how you think about a situation and you will change how you feel, which will change how you behave.
The dichotomy between mind and heart is a false one. The truth is that we have emotions tied to different thoughts. The dichotomy isn't between thoughts and emotions, but competing thoughts, and these thoughts cause emotions of varying degrees of intensity. If our "rational" thoughts don't evoke strong feelings, then our "irrational" thoughts (thought of as desires) may be emotionally charged, and it will seem like the conflict is between thoughts and emotions.
At the end of the day, all our actions are driven by emotions, whether those that we experience or those that we suppress (leading to inhibited action or inaction, which should also be thought of as action. In other words, choosing not to go out is an action you've taken based on the emotions you experienced, and the thoughts that led to these emotions).
The thoughts -> emotions -> actions isn't this simple, but the model helps in understanding the connection between the three elements. What you eat can influence how you feel, which changes the thoughts you bring your attention to, leading to a virtuous cycle of positive emotions and positive actions.
What's also crucial to recognize is that our actions can also shape our emotions, which can change our attitude (towards ourselves, those around us, and life, in general).
One of my favorite quotes is by Barbara Baron: “Don't wait for your feelings to change to take the action. Take the action and your feelings will change.”
You don't have to feel motivated to go to the gym. Go to the gym, and you'll feel motivated.
This principle applies to many aspects in life, and it's important that we make the most of it.