However, a break in the training week saw the majority of the squad travel a couple of hours by bus to take a tour of the German concentration camp.
"It's been a real eye opening day, normally when you get a group of 30 rugby players together for a trip there is a certain mood, but we have all been contemplative today to say the least,"said Williams.
"As a family man myself to go into the second camp and see all the belongings that had been kept from the prisoners and the human hair that had been shaved from their heads was the most sobering thing.
"There were clothes and shoes and other belongings but, when you see the children's toys and you realise what that means in terms of who was housed here, and what probably happened to them it's difficult to comprehend.
" There's no point in me trying to find the words, better men have tried, but the whole concept of the site is horrendous. We thought it was important to go and I think we are all glad we went.
"We've found out a little about the place we have been staying and its history, but we have also been to a site of huge historical significance and it is something that will stay with me and, I'm sure, everyone else forever."
One of the players accompanying Williams was teenage Scarlets wing George North, who is still only 19-years-old but has a genuine thirst for knowledge about the places he has been privileged to visit as a professional rugby player.
"It's just one of those once in a lifetime experiences you have to do when you get the chance,"said North.
"The only thing I know about the second world war is from what I have read at school or seen in movies, but the visit went beyond any expectations I had.
"Just imagining what these people were going through as they arrived here on the trains not knowing what was going to happen to them is extremely sobering.
"We've seen the cramped conditions they had to put up with and also the clothes and shoes and even human hair that is all that is left and it just makes you realise how privileged you are to be alive.
"We know we have been working hard, but we have always known we lead privileged lives as professional rugby players.
"Today's visit just helps put that into perspective and makes you more determined to appreciate what you have in your lives from your job to your loved ones."
Both players have four days left on the Polish training camp which is allowing them to train for twice as long each day and both are relishing the experience and hoping to get on the next camp which runs from Saturday 16th to Monday 26th July.
"I'm feeling good and most of the boys are saying the same thing,"added Williams.
"I look around me and certainly in the forwards there's only me holding the fort for the more senior players.
"There's Shane with the backs and obviously Stephen (Jones) who has stayed home for this one, but apart from them we have a host of great youngsters and they are all pushing themselves.
"To a man we are putting the effort in and the training regime has certainly met with all my expectations in terms of how tough it has been.
"I spoke to a few people before I left about what to expect and I haven't been let down, but it's a holiday camp compared to what we have witnessed today and I'm still hungry for more.
"We all want to make sure we are on that next camp and doing it all again and everyone is desperate to make that World Cup squad."
North may be looking to go to his first Rugby World Cup, as opposed to Williams who is targeting his fourth, but he is just as hungry to be involved in that campaign and the warm-up matches against England and Argentina in August.
"It's certainly been tough, but we wouldn't have it any other way and we have been able to get a lot of good rugby work done as well,"added North.
"This is what a pre-season is all about and I'm just enjoying the experience at the moment and not looking any further than that second camp.
"I want to get on that and take it from there. Being in your national rugby squad is a huge privilege and, if ever it was needed, experiences like today just hammer that home to you."
The Olympic Training Centre in Spa?a is one of the most advanced sports centres in Europe, with extensive sports facilities: an athletics stadium, a tennis court, basketball and volleyball courts, an indoor swimming pool, weights room, cryo-rehabilitation rooms, electrotherapy, physiotherapy and magnetotherapy rooms.
Tickets to the Wales vs England Rugby World Cup warm-up match at the Millennium Stadium on Saturday 13 August (kick off 2.30pm) are priced £30 and tickets to the Wales vs Argentina on Saturday 20 August (kick of 2.30pm) are priced at £25 and are on a 'buy one get one free' promotion.
Fans can also purchase their tickets for the Millennium Stadium clashes offer online at www.wru.co.uk/tickets or by calling the ticket hotlines 08442 777 888 or 02920 230130 or at local Tesco stores from Thursday.