We tend to ask ourselves a simple question when faced with a major personal decision. 

Say you're considering whether to start a business. Or change careers. Or set out to accomplish a huge goal.

If you're like most people, the decision usually comes down to this:

"Will (this) make me happy?"

The problem is, where major personal decisions are concerned, we tend to be terrible at predicting what will make us happy. For example, plenty of entrepreneurs build successful businesses only to discover they love working in, but not on, their business. 

And we also tend to be terrible at using happiness as a filter for smaller decisions. Sure, binge-watching Broadchurch on Netflix sounds like a recipe for happiness. But if you're like most people, you also feel guilty for not having spent those hours doing something more "productive."

That's why the "happiness" question often doesn't work.

But here's a question that does. In his book What Matters Most: Living a More Considered Life, Jungian psychoanalyst Dr. James Hollis recommends asking a different question:

Ask yourself of every dilemma, every choice, every relationship, every commitment, or every failure to commit:

Does this choice diminish me, or enlarge me?

Say you're trying to decide whether to start a side hustle. Predicting whether your side hustle will make you happy is impossible. 

Predicting whether it will enlarge you is not. Start your own business and you'll naturally gain new skills. You'll meet new people. You'll gain new perspectives. You'll learn things, especially about yourself.

Even if your side hustle isn't particularly fun, and even if it fails...it will enlarge you.

Or say you're trying to decide whether to embark on achieving a personal goal. Plenty of people describe feeling empty after achieving a major life goal; crossing "run a marathon" off your bucket list might not make you happy.

But training to run a marathon will definitely enlarge you. You'll build greater self-discipline and perseverance. You'll improve your health and fitness. You'll build relationships with people on the same journey. You'll learn things, especially about yourself.

Even if the happiness you feel from crossing the finish line doesn't last long...you will be enlarged by the process. 

As for being diminished? If you're a leader, choosing to ignore an interpersonal conflict between employees might "feel" good in the moment (avoiding conflict usually brings a sigh of relief), but deciding to ignore the problem reduces your effectiveness as a boss and may diminish how you view yourself as a leader. Or deciding to take a business short-cut--while the near-term results might make you happy, the prospects for your business could be poorer over the long term. Taking that short-cut might diminish how you view yourself as an entrepreneur.

Try it. Whenever you have a choice, ask yourself one question: "Does this choice diminish me, or enlarge me?"

Then, whenever possible, choose enlargement. (Hint: It's almost always possible to choose enlargement.)

While it might not be fun, especially in the moment, to push past your comfort zone, the only way to grow--the only way to enlarge yourself--is to do things that make you a little uncomfortable.

But oddly enough, since success and fulfillment tend to walk hand-in-hand, you'll likely find the result leaves you feeling happier as well.

Because the closer you get to the person who you aspire, deep inside, to be--the more your self-image matches the reality--the happier you will be.