Many people spend their 20s getting some unhealthy behaviors out of their system — like sleeping until 2 p.m. on Saturdays and spending all their disposable cash on new kicks.

But your 30s are an ideal time to cement the habits that will help you achieve personal and professional fulfillment for the rest of your life.

To give you a head start, we sifted through recent Quora threads on this critical life transition and highlighted the most compelling responses.

Here are 10 lifestyle tweaks you can make in your 30s to lay the foundation for lifelong success:

1. Stop smoking.

If you've started smoking, stop immediately, suggests Quora user Cyndi Perlman Fink.

While you can't undo the damage you may have already incurred from smoking, research suggests that those who quit before age 40 have a 90% lower mortality risk than those who continue.

2. Start going to sleep and waking up at the same time every day.

It might be tempting to use the weekends to recoup your sleep debt, but Nan Waldman recommends you hit the hay and wake up around the same time every single day.

If you oversleep for even a few days, experts say you risk resetting your body clock to a different cycle, so you'll start getting tired later in the day. Avoid a lifetime of sleep issues by sticking to bedtime and wakeup routines whenever you can.

3. Start exercising regularly.

"Try to move yourself as much as possible," says Alistair Longman. "It doesn't matter if it's walking, cycling, running, weightlifting, hiking, swimming — as long as it involves some movement."

In the later half of your 30s, you start losing muscle mass, so it's especially important to exercise at this time. But remember to choose physical activities you really love, since you're less likely to continue exercising if you dislike your workouts.

4. Start keeping a journal.

"Journal your life! Your written records will entertain and endear in your future," writes Mark Crawley.

Even if you'd prefer to keep your musings to yourself, putting your thoughts and feelings on paper can help you deal with stressful events.

5. Start saving money.

"Building the habit of saving early means you'll continue it further down the line," says Cliff Gilley.

It might seem like your golden years are a lifetime away, but the earlier you start saving, the more time your money has to accrue interest.

6. Start pursuing a life dream.

"Don't delay pursuing your life goals," writes Bill Karwin. "Want to buy a house? Have kids? Write a book? Pick one of those life goals and get started. What can you do between now and the end of the year to embark on one of them?"

7. Start learning to be happy with what you have.

"If you are content with what you have, you will have a happier life," says Robert Walker.

It's really about gratitude: Research suggests that appreciating what you have can increase happiness and decrease negative feelings. Perhaps that's why Oprah Winfrey kept a daily gratitude journal for years.

8. Stop thinking you need to satisfy everyone.

"After I reached 30, I stopped feeling the need to please everyone. You can choose your friends and contacts more carefully," says Kevin Teo. In particular, Teo realized he wasn't obligated to be nice to people who were unfriendly toward him.

Whether you decide to whittle down your Facebook friends to a mere 500 or simply hang out more with the people who make you happy, it's important to invest your time and energy wisely.

9. Stop comparing yourself to others.

"If you are unable to do some things in life compared to your siblings and friends, then please be at peace with yourself," advises Mahesh Kay. "Don't be harsh on yourself."

As one psychotherapist writes, constantly peering over your shoulder to see what others are doing doesn't help you accomplish your goals. You'd be better off spending time thinking about what you want to achieve and evaluating your progress on those fronts.

10. Start forgiving yourself for your mistakes.

"Forgive yourself your mistakes. We all make plenty of them. Don't dwell on the errors of the past — learn from them, let them go, and move ahead," writes Liz Palmer.

One social psychologist says that self-compassion (the ability to forgive yourself and learn from your mistakes) is the key driver of success. That's likely because people who practice self-compassion see their weaknesses as changeable and try to avoid making the same errors in the future.