While science has identified hundreds of different neurotransmitters in our brains, there are a number that are most commonly identified with behaviour.

Each of these are part of our survival mechanism and will encourage or discourage specific behaviours with the goal of keeping us safe. Quick side note: Not all of these technically are neurotransmitters, although all of them can behave as neurotransmitters, so for the purpose of this article I’m lumping them all together.
Dopamine is that reward for doing something. When we check something off our todo list, we get a hit of dopamine. Note that we get that dopamine for taking any step, whether or not that step actually moves us forward. Our brain is rewarding the fact that we took action only and is not making any judgement on whether the action was positive.
This sometimes leads to the wrong behaviours as we’re getting rewarded for being busy, not being effective.