Having lost the opening match of the series, the Wallabies made it one win each with a 16-15 victory over the tourists in Melbourne on Saturday.
Despite the defeat, Parling insists that the only way to recover from the loss is to go out and win the tour in the deciding Test match.
"We'll find out how hard [it will be to turn things around] but I can tell you now we are absolutely devastated. For a lot of us, it's the biggest game of our career to date and to come so close to winning the series, it's more than hard to take," Parling told the official Lions website. "Andy Irvine (Lions tour manager) spoke afterwards in the changing rooms that we have another crack at it, that we are almost in the same position we were in the morning and that we can still win the series. But it's hard to take.
"We have to learn the lessons from it. We got ourselves in a good position in the game. We did fairly well throughout and they sneaked in and we still had a chance to nick it at the end. It's going to take the whole squad to pull together. It's all part of this tour and being professional. You have to get yourself back up for it again and go and play. If you can't get up for the deciding game of the tour, then you have a bit of a problem. I'm sure we'll get there.
"That's what we've got to do, isn't it? That's rugby. Look, there certainly are positives to take from it... but we've got to get ourselves up for it. The series is still there for the taking. We have to make amends. What does it set up? Does it get any bigger than next week? We have one more chance, one more crack. For most of us, we might never be on a Lions tour again. For the majority of players it's a once-in-a-lifetime opportunity. There's one more opportunity, one more in the series. We have to get on with it and have a good crack."
The deciding Test takes place in Sydney on Saturday.