The 21-year-old sprang somewhat of a surprise at the British Gas Championships at the London 2012 Aquatics Centre back in March, winning the Battle of Bath to take 200m breaststroke gold.
In touching home first in 2:09.33 minutes, Willis set an impressive new personal best ahead of fellow Bath-based swimmer Michael Jamieson, who also qualified for London 2012.
In third place however was another teammate Kris Gilchrist, who did not make it to London 2012 and having sealed the Bath and British honours, Willis is adamant the hard work starts now.
"I was really happy with my performance at the British Gas Championships, I don't think it could have gone much better for me," said Willis.
"I got a huge personal best in the 200m breaststroke and I qualified and it was just a huge relief for me. Then with all the excitement it starts to sink in a bit more and you begin to think that this is really happening.
"I'm just looking to pick up the work again now. We've got a few competitions lined up and then I want to knuckle down and arrive at the Olympics knowing I've done everything possible to be as ready as I can and have no regrets.
"It's a once-in-a-lifetime opportunity and I'm really happy that it's my first Olympics and it's so much more special that it's in London - I'm pretty sure it will be my best even if I go to other Games."
With Gilchrist's Olympic hopes in tatters, he won't be seen on the swimming scene competitively again but Willis, the youngest of the trio, admits he is in his former teammate's debt.
"I'm still in touch with Kris but it is strange that he's gone. It was difficult that there were only two spots for three swimmers and we always knew it would be difficult," added Willis.
"But he's still in touch and still giving me a bit of stick about being the youngest one but he's a great guy and I learned a lot from him.
"And Michael is another example of a great athlete to test yourself against regularly, he's another good friend."