LONDON -- In the crush and mom forced by boys sex videoscrowd of our daily commutes, it's easy to lose sight of the positive aspects of the day ahead.

But one Londoner is trying to make a difference in other people's days by leaving notes for strangers in public places.

Designer Andy Leek told Mashable that going through a period of mental illness was his inspiration for the project.

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"It was caused by working too hard, commuting for too long and not looking after my mental well being. I noticed that commuters looked really miserable so wanted to try and make a difference in other peoples days," Leek told Mashable.

People have taken to Instagram to post photos of the posters and send positive messages to Leek.

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Leek started off creating small handwritten notes that he hid in copies of the free newspaper Metro which he then left on empty seats on public transport for people to discover. After leaving around 400 such notes on public transport, Leek decided to start pasting posters with his messages so he could reach more people.

"Once I started I realised how much fun it is to head out into the city at night and create street art while the rest of the city sleeps. The slightly illegal nature of the project just added to the fun and sense of adventure," Leek said.

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In the UK, putting up posters in public spaces can land you in trouble with the local authority and result in a fine.

"I am always careful not to paste them on anyone's direct property, always using electrical boxes or the back of phone boxes. I am fully aware that I might get fined, and accept it as a part of what I am doing," Leek told Mashable.

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Leek's had over a hundred people upload pictures of the posters and he's received countless positive responses.

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"Lots of people [are] saying that my messages struck a chord with them and that it made a difference to their day. It is this that keeps me going with the project," Leek said. "I see this as a wonderful serendipitous collaboration with strangers," Leek said