The Cardiff Blues winger was limited to just 15 appearances for his region and only two Test appearances from a possible 10 for Wales last term.
An ankle problem ensured the 22-year-old did not play any part in the autumn Test engagements against Australia, South Africa, Fiji and New Zealand, with a foot injury keeping him out of the following Six Nations until Wales' final fixtures against Ireland and France.
A recurrence of the foot problem meant surgery was required, bringing his season to an early end, and Halfpenny, first capped as a 19-year-old in 2008, has revealed the heartache he felt watching the likes of George North stake a claim for his wing slot during his enforced absence.
"It has been the hardest season of my career," he said.
"To keep suffering injuries just when I have been getting back to fitness was incredibly frustrating.
"Seeing someone else in the jersey has been very hard and I have been grateful for the support I have received from my friends and family. They have been superb, as have the fitness guys at the Blues and with Wales."
Halfpenny's foot is still in a protective boot but he will travel to the first of Wales' two World Cup training camps in Spala, Poland next week.
Coach Warren Gatland has admitted the current injury means Halfpenny is a doubt to be ready for the World Cup but the 19-cap three-quarter is hopeful of being ready to play a part in Wales' warm-up Tests against England (twice) and Argentina in August.
Halfpenny, who was speaking at the launch of Wales' Under Armour kit for the World Cup, said: "I am still carrying the injury at the moment and my foot is still in a boot but I have been selected for the first cap in Poland.
"I have been doing plenty of work in the pool to try and help strengthen it, including walking on a treadmill under water so I don't put all my body weight on the leg.
"I will be doing a lot of similar stuff out in Poland and hopefully I will be able to do some walking before the end of our time there. The idea then is for it to be strong enough that when I remove the boot I can start running work straight away.
"I am looking at (playing in) the second England game or the Argentina game a week later. The aim is to be fit for Argentina but hopefully I might be ready for the England game but we'll see how it goes."
Halfpenny's absence coincided with the emergence of Scarlets teenager North among the Wales ranks, with the 18-year-old grabbing two tries on his Test debut against South Africa and also touching down against the Barbarians last month.
North's regional colleague Morgan Stoddart and Newport Gwent Dragons flier Aled Brew have also impressed when given the chance to fill one of the wing places, and Halfpenny acknowledges he faces plenty of competition if he is to win back his place.
"I think the competition is greater now than when I came into the side," he said.
"There are a lot of good guys in the back three and you need to put your stamp on it when you get the chance.
"George North has taken his chance very well. In a way his chance was similar to mine as I came in when Mark Jones was out injured.
"It happens and it is part of the rollercoaster of being a professional rugby player. When you are injured it's the test of the man to come back and hopefully that's what I will do."
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