This is because you haven't found something that genuinely interests you.

How do you know you found it?

Time will fly. You will not think about doing that thing at all. You might dread going to sleep because you want to keep working on it. You want to talk about nothing else. You are happy and satisfied despite the hard work and difficulties.

For me it has always been creating technology first and engaging with people (customers). I discovered the second one later in life as I had to learn to sell the products I was creating. It turned out that, for me, the combination of creating the technology and then engaging with customers was my utopia. I worked so hard I ended-up in the hospital a couple of times from exhaustion and dehydration (don't do that). I really enjoyed organizing and running our trade shows and customer presentations all over the world. In fact, I ended-up craving that level of contact as a way to balance the engineering side.

Not sure how old you are. There are phases to everyone's lives. How you think of the world when you are younger and single is very different from when you are older and have your own family. Different yet from when you have experienced some success and failures. And, sadly, different yet as, later in life, you experience friends and family pass. What was important at the start of the journey quickly ceases to be important later in life for various reasons, experience, pragmatism or perspective.

In other words, there is no easy answer.

You have to consider that you might not be in a field that stimulates you enough to give you that natural joy that requires no conscious effort. I'll leave it to others to suggest how you might engage in a search for that unique thing that meshes perfectly with your DNA. I was lucky in that I had a pretty good idea of what I wanted to do and what I enjoyed doing very early in life. For me there is not real difference between work and play. I don't care about hours of the day or holidays. Other than hanging out with my kids and family, if I am awake I am doing what I love, which happens to be my work. Still, work-life balance is crucially important.

I also teach my kids that we can't always do what we want and that we actually have to learn --and force ourselves-- to do those things we don't want better and more efficiently than perhaps other things. In other words, if you are responsible for doing something you don't really like to do, be the best at it and get it done fast and well.

Two personal examples of this:

I hate shipping. By that I mean, putting things in boxes and doing the paperwork. This is particularly ugly when it comes to international shipping. And so, I made it a point to put in systems and tools in place to optimize and automate as much of this as possible...because I hate doing it but I must do it.

The big one was one of those "be careful what you wish for" examples. We decided to remodel our bathrooms. Wanting to save money I decided to do the work myself. I am no stranger to construction and quite capable, so that wasn't an issue, I could build a house from scratch. I would soon discover that crawling on the floor to tile two full bathrooms was, well, a nightmare and something I did not enjoy at all. The first couple of weeks were as painful as could be, as my body adapted to literally being on my hands and knees for eight+ hours per day. In order to get it done faster and correctly I bought the best professional tools and subscribed to a paid service that teaches you about this kind of remodeling and answers questions.

In this last case my kids knew, without a shadow of a doubt, that I hated --absolutely detested, with every cell in my body-- what I was doing. I dug a hole and I was the only one who could crawl out of it. Teaching moment. I had them help for a bit so they would learn and also understand what responsibility means, even in the face of something you detest. We got it done and it's architectural-magazine perfect. And I am glad it's over. I will NEVER do that again.

Anyhow, the point is, developing motivation for doing things you hate could be valuable. This is my experience and might not necessarily apply to everyone.

Explore and see what makes you tick. Don't assume you know what drives you until it is beyond obvious.