Jamie Roberts: Leaving Cardiff is tough but nothing beats the red jersey of Wales

It is great to be back in a Wales shirt. Simple as that. It only takes a game away from the red jersey to make you appreciate it and realise how much you do value it. It means a huge amount to me. I have missed not wearing it.

Wherever I end up playing my club rugby, I still harbour very strong ambitions to play international rugby. That is the major driving force for me – as personal goals go it is a huge ambition, but I also feel it is the time in my life to experience something new.

My priority is to enjoy every day in life, to enjoy every day training or studying for my medical exams. I'm making a move in my career for a new challenge in life and there is nothing wrong with that. I will tell more of my reasons after the autumn because my immediate focus – as everyone would and should expect – is on this afternoon and then the games that follow Argentina.

Leaving Cardiff is hard – it has been a very, very hard decision and one that took ages to make. The decision is multi-factorial but I am sure I have made the right choice at this stage of my life. You have to weigh everything up and make the call when you think it is right.

Right now it is about playing for Wales again. I have been playing international rugby for five years but when that moment comes for the team sheet to be read out I still get nervous. After being out through injury, sitting there out of the picture, you do wonder whether you can get back in. It was a great feeling to hear my name read out – now it's time to justify my selection.

The build-up has gone well. You have to be able to separate what might be going on off the pitch with what is happening in training. I believe I have the ability to do that and a lot of it has come from my academic work outside of rugby, having to balance both careers. When I go to uni I completely switch off from rugby. When I get on to the training park or the playing field I divorce myself from everything else and everything outside rugby. That ability to flick the switch on and off is paramount in professional sport.

The last memory I have of wearing a Welsh shirt was when we paraded the Grand Slam trophy around the Millennium Stadium back in March. I missed those games in Australia and massively felt for the boys. It was heartbreaking watching it on TV. We came so close, losing one Test by a point and another by two.

But it can be a stepping stone. This squad is maturing and has improved over the last couple of years. Now we want to take the next step and that is winning against southern hemisphere teams. We toughened up with a week back in Poland. The squad needed that, a chance to sharpen bodies and minds in an environment away from home.

There are a few new faces around and it's great to see Aaron Jarvis get his first cap. He has put in some solid displays for the Ospreys and is a player who we need to come through with Adam Jones having played a lot of rugby. Getting that depth to the squad is so important.

With Jonathan Davies injured, I will be alongside Scott Williams in the centre today. Scott is one of the most improved players over the last couple of seasons. Certainly leading up to the World Cup, his speed of development as a player was pretty frightening. He came a long way in a short time and played very well at the World Cup. We have gone well in training this week but we will be judged on what we do in the Millennium Stadium this afternoon.

Wales' first fixtures in Gatland's absence

It is my first time back in the squad with Rob Howley in charge while Warren Gatland is on his Lions sabbatical. The coaching group under Warren, as far as the players are concerned, come as a team. Warren is at the head but the work Rob, Shaun Edwards, Robin McBride and Neil Jenkins do as a quartet is second to none. They have played at the highest level and coached at the highest level, they know what they are doing.

Will a Howley Wales lead to a gameplan noticeably different to Gatland's? I can't divulge too much! We are a team that likes playing rugby. There are a lot of talented players in the squad who thrive in being put into space and expressing themselves. It's finding the right way to do that. To get wins against southern hemisphere sides we have to play a bit smarter – there are times to play rugby and there are times to play percentages and we know if we get that balance spot on this autumn we will be in with a good shout.

But right now we are not looking past the first game – of course that's a cliché but it is the only way to approach any game at any level. Argentina are a strong, talented outfit who have played against the best sides in world rugby over the last couple of months in their first Championship. That intensity will have made them a much better team.

Jamie Roberts is a Wales and Lions centre