In this exclusive interview, British fashion designer Paul Smith shows Dezeen his new exhibition at London's Design Museum, which contains a room "nicknamed the paracetamol room, because by the time you come out you'll probably need an aspirin". Update: this interview is featured in Dezeen Book of Interviews, which is on sale now for £12 (+ movie).

The show called Hello, My Name Is Paul Smith, which opened today, celebrates Paul Smith's career to date and reveals insights into his creative processes.

"The whole point of the exhibition is really about encouragement," he tells Dezeen while sat in a recreation of his cluttered Covent Garden office that has been created at the show. "It hopefully gives you the encouragement to think, well, 'I can move on from a humble beginning'," he says.

Visitors enter the exhibition through a three-metre-square cube that simulates Smith's tiny first shop on Byard Lane in Nottingham, which was only open for two days a week. Smith's Covent Garden design studio has also be recreated, with material and pattern samples strewn amongst sketchbooks and colour swatches.

In a room called Inside Paul's Head, images of flowers swirl around screens before morphing into prints covering Smith's garments and accessories. "It's nicknamed the paracetamol room, because by the time you come out you'll probably need an aspirin," Smith jokes.

The next space is a hand-painted wooden mock-up of the Paris hotel room that Smith used as his first showroom during Paris fashion week in 1976.

"I think it was six shirts, two jackets, two jumpers and nobody came," he recalls. "Monday, Tuesday, Wednesday, nobody. I was leaving on Thursday and one person came at 4 o'clock, and I was in business."

There's also a section dedicated to Smith's photography: "I've been taking photographs since I was 11. My Dad was an amateur photographer and his original camera is there on the wall. I shoot all our advertising and promotional material but also work for lots of magazines as a photographer."

Smith's collaborations over the years including a MINI car and a pair of skis painted with his signature colourful stripes are displayed together, along with cycling jerseys and a giant rabbit-shaped bin he has worked on.

"It's really interesting for me to see," he reveals. "They're usually all hidden away somewhere. Seeing them all together is like 'Oh wow! We've done quite a lot over the years'."

A wall covered in 70,000 buttons is used to demonstrate the unique elements found in each of the brand's stores worldwide, such as a room decorated with 26,000 dominoes at his recently extended Albemarle Street store in London's Mayfair district. "It shows my passion to make sure all out shops are different," he says.

Garments from Smith's archive flank both sides of a long white corridor and are grouped into themes rather than age, while a movie documenting Smith's most recent menswear show is played in the final room.

The exhibition is laid out around a central space lined with a pictures from Smith's personal collection, encompassing photographs by Mario Testino to framed drawings sent by fans.

On the way out, a giant Post-it note on the wall reads "Everyday is a new beginning". Smith finishes by saying: "The idea is you come here, you get inspired, then the next day is the rest of your life."

The exhibition was curated by Donna Loveday and runs until 9 March 2014 at the Design Museum.