Hales, playing in his second test, made 60 at Newlands as England hit 317 for five on the opening day of the second test against South Africa.
"I was disappointed not to go and make three figures," he told reporters as the tourists, 1-0 up in the four-match series, ended the day in a strong position.
"Every time you play international cricket there is always something to prove and this is obviously a new challenge for me and my career and it's something I have loved so far.
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"I've tried to stick with what I've done in the past," said Hales in answer to a question about a change in his swashbuckling approach from the limited-over format.
"Obviously there is going to be stuff I tinker with and learn the more games I play. The important thing is to be true to myself but to keep looking to improve in certain areas.
"I guess I do get mis-cast at times. Most of the public will only have seen me play Twenty20 and ODI cricket so I guess I do have that label," added Hales.
England are still looking for a reliable long-term opening partner for captain Alastair Cook, having gone through eight in 39 tests since Andrew Strauss retired in 2012.
"Opening in five-day cricket is something very different and something I’ve worked hard on in the last two years. I do approach it differently to a Twenty20 or an ODI," said Hales.
(Editing by Tony Jimenez; mark.gleeson@thomsonreuters.com; +27828257807; Reuters Messaging: Reuters Messaging: mark.gleeson.thomsonreuters.com@reuters.net)
