How can I tell whether this loss of interest is a temporary pause caused by my current pressures or whether something important in me is disappearing?

How can I understand what may be happening to me when this lack of energy and desire keeps occurring alongside physical and mental problems?

Recently, I have had very little desire or energy to do anything, even to eat, and I have also noticed problems affecting both my body and my mental state. Today, although the heavy rain made me feel relaxed, I stayed home, did a little work, skipped a meal, and still felt tired.

What small, realistic steps could I take to ease this state and gradually regain some energy or interest?

For about six months, I have had very little energy or interest in things, and when I am idle I mostly stare blankly. I find it difficult to seek professional help.

How can I make sense of having invested so much and chosen to stay, then losing the dream anyway, so that I can move forward?

I spent several years on a hardware project that began with enthusiasm but became draining through ineffective communication and overtime. After a failed acceptance and colleagues being dismissed, I chose to stay because a new leader and the hardware market gave me hope. Although we eventually passed acceptance, budget constraints stopped the product from being updated, and I realized the project was finished.

How can I make sense of this loss and move forward after giving so much of myself to a dream that did not find a market?

I spent about five years building a working robot device and funded a company around it, but after several years no customers bought it, and we are now closing the company. I understand that we failed to test whether users actually needed it, but I still invested much of my life in the dream.