Celebrities face a lot of pressure to look a certain way, whether it's because they want to play a part in a movie or because they're under constant public scrutiny.

That being said, the best celebrity transformations are the ones that are achieved through confidence and/or perseverance.

Here are 11 famous celebrities who feel good about the changes they've made to their appearance.

Mark Wahlberg

The Pain & Gain actor is well-known for his tough-guy attitude, and he's worked hard over the years to maintain a body that compliments the personality.  

Scott Thompson (Carrot Top)

Th iconic red-haired comedian went through quite the transformation to achieve his dream look. Despite his denial on going under the knife, it's unclear how his face looks like it got a facelift. All that can be said is that he's happy and confident about his new look.  

Matthew Lewis

Geeky Neville from Harry Potter is another Hollywood star known for his dramatic transformation. He persevered for that dream look and nailed it.

Adele

Adele revealed that cutting sugar from her diet helped her to lose weight. She said she used to drink 10 cups of tea a day with two sugars in each. But she can't deny that her meals, supplied by Pure Package, contributed to her healthy lifestyle and gradual weight loss.

Jennifer Hudson

Grammy and Oscar-winner Jennifer Hudson turned heads in 2010 after she lost more than 80 pounds. She even went on to become the ambassador at Weight Watchers. Although she parted ways with the weight loss program in 2014, she's proud of her dedication and accomplishments.

These next ones may be a shocker!

Zac Efron

The High School Musical star is no longer the slender teenager he once was.

Josh Peck

The Nickelodeon child actor who was known for his weight is not as recognizable now. He said it's all thanks to his personal trainer and his new eating regimen.

Calvin Harris

Music producer Calvin Harris was described as awkward, scrawny and emo in his teenage years. As he rose to fame, his image completely changed. Now he models for Armani briefs.

Chris Pratt

Actor Chris Pratt lost 60 pounds in 6 months. He said goodbye to his belly and hello to a 6-pack.

J.K. Simmons

Actor J.K. Simmons has been motivated to maintain a healthy lifestyle as he ages. He abides by an intense workout routine that puts into question his 62 years of age!

Oprah Winfrey

The talk-show billionaire said a few years back that she didn't want her thyroid condition to dictate how she lives her life. Her weight fluctuated over the years and she finally decided to call it quits with dieting in 2010. Oprah has proved that a dream body is simply a confident body.

What's your opinion on these celebrity transformations?