Feel like you don't have enough time to do what you want to do? You're not alone: One survey shows nearly half of the respondents feel time-constrained.

Since it's impossible to create more time, though, the answer is to free up more discretionary time -- the more the better.

Or not. A study just published in the Journal of Personality and Social Psychology found that while experiencing a lack of discretionary time every day leads to feeling more stressed and less happy (no surprise there), the researchers found and "internally [replicated] a negative quadratic relationship between discretionary time and subjective well-being." 

Which is just a fancy way of saying that too little free time makes you unhappy, but so can having too much free time.

The sweet spot seems to be between two and five hours of free time per day, but with a bunch of caveats.

The first is how you define "free" time. For some, free time is chill time. Couch time. Netflix time. Doing "nothing," but in a good way. For those folks, the sweet spot likely falls closer to the two-hour end of the free-time spectrum.

For others, free time is exercise time. Connecting -- genuinely connecting -- with family and friends time. Working on a side hustle time. Working on yourself time. Actively doing things you want to do because you feel they are good for you or for others. For those folks, the sweet spot likely falls closer to the five-hour end of the free-time spectrum.

Why the difference? The researchers found that an abundance of discretionary time is linked to lower subjective well-being due to lacking a sense of productivity. Free time is great, but past a certain point, vegging and chilling and hanging out leaves people feeling lazy. Sluggish. Like the time they just spent was wasted.

In short, unproductive.

On the flip side, more free time leaves people feeling happier when they spend a portion of it on productive activities. Like building and maintaining relationships. Like working on a project. Like reading. Like exercise. 

Keep in mind "productive" doesn't only mean work. "Productive" means doing anything you feel has a purpose. "Productive" means doing anything you feel makes your life better.

Which may mean adjusting how you approach certain activities.

Take exercise. Don't go to the gym and mindlessly slog through an elliptical session. Knock out a challenging workout that will help you achieve a fitness goal. Do that, and your exercise time will improve your actual well-being and will make you feel a little happier -- because now it feels productive.

Or take chilling. If you want to watch TV, great: But don't just settle for whatever seems to be the best option at that moment, because that will leave you feeling you wasted some of your free time. Know ahead of time what you'll watch if you get the chance. Watch something you really want to watch. You'll enjoy the experience a lot more, and you'll feel like the time you spent watching TV actually had a purpose.

Then, in a larger sense, pick something you want to achieve. Pick something that you want to become.

Then use some of your free time -- no matter how little you might feel you have -- to actively work towards it.

Not only will you enjoy the sense of accomplishment that comes with progressing towards a goal -- even if that "goal" is doing something purely for fun -- but you'll also feel better about yourself and your life.

As with most things, too little of anything is a problem. Yet so is too much.

The key is knowing how to best use what you have in the way that leaves you feeling fulfilled and happy.