7 'bucket-list' items you can stop worrying about completing in your 20s

It's a surreal experience: Having all your friends standing at mile 26.2, cheering you on as you cross the finish line. And sure, you're probably in better shape to run a marathon now than you'll be a few decades down the line.

And yet. As Business Insider's Erin Brodwin reported, distance running could be bad for your health. Some research suggests that prolonged, intense exercise is related to reduced immune function and digestive issues.

Brodwin suggests interval training as an alternative to training for a marathon: You work as hard as possible for a few minutes, then rest, then repeat. It may be more beneficial for your health.

If you're still set on those miles, you can do them at 31.

Being confident in your appearance is a great thing — something you should strive for. But if you still have some hang-ups — your skin, your weight, your hair — it's OK. Most every 20-something feels similarly about themselves.

In fact, as Business Insider's Chris Weller reported, a Gallup survey found body image peaks after age 70. About 75% of men in their early 80s agreed with the statement, "You always feel good about your physical appearance." And about 70% of women around age 74 agreed with the same statement.

If you're single and in your 20s, there's a solid chance you're on a dating app. Which means you have 24/7 access to thousands of other eligible 20-somethings. How do you choose among them?

The truth is, many of those people could turn out to be a good match for you. As couples therapist Esther Perel previously told Business Insider, there's no such thing as "The One." Perel said: "There is a one that you choose and with whom you decide that you want to build something."

From there, you put in effort to make your relationship with that person as strong, and as fulfilling, as possible.

On a similar note, keep in mind that you'll probably never land your "dream job" — in your 20s or afterward.

"Look for a job that is in the general direction of your skills and passion," behavioral economist Dan Ariely previously told Business Insider, and then make it fit better.

As leadership expert Simon Sinek previously told Business Insider, "If you think it's that way" — i.e. if you think the perfect job will miraculously appear — "then you're going to keep going from job to job to job to job, and unfortunately you'll never find what you're looking for."

For most people, telling your manager you're leaving is a lot less exciting than it is in the movies. Even if you're incredibly frustrated at work, and long for the sound of the door slamming behind you for the last time, you might not be in the position to be able to leave. Since you're there anyway, consider seeing how you can tweak the job to suit you better.

Stanford professors Bill Burnett and Dave Evans recommend keeping a "Good Time Journal." The first part is an activity log, where you list your primary activities and how engaged and energized you were while doing them.

The second component is reflection, which involves reviewing your activity log and noticing any patterns or surprises. See if you can eliminate those tasks you don't enjoy — and maximize the amount of time you spend on the ones you love.

Workplace experts extol the virtues of networking — forging mutually beneficial professional relationships by showing up to events like conferences and happy hours.

Wharton psychologist Adam Grant shared a slightly different take in The New York Times: Instead of focusing on schmoozing, focus on working hard, and let those relationships form naturally. If you develop a reputation for being one of the most knowledgeable workers in your field, other people will necessarily be drawn to you.

If you're planning to have kids, and/or pets, and/or a mortgage, then yes, it will be harder to book a last-minute flight to Australia when you're older.

But there's no point forcing yourself to create experiences that aren't meaningful to you. INSIDER's Kristin Salaky reported that, at 24, she's never been outside North America, partly because she's anxious about flying and partly because she prefers other kinds of closer-to-home excitement.

Travel is supposed to be fun — not a burden — so don't let that list of places you haven't yet been stress you out.