We need amino acids from protein to create neuro transmitters dopamine and adrenaline needed for motivation and mood. Many of us are not getting enough protein from the diet in particular vegetarians and vegans need to be aware. Not getting enough protein can have a direct impact on the way that we feel. Also, we may not be absorbing the protein that we are eating - lots of us have low stomach acid, especially if under stress or taking ant-acids. Adequate stomach acid is essential for breaking down the protein from the meal and absorbing it so it can be used for neurotransmitters.
These are all things that we can assess and address during a nutrition consultation.