A year ago Jagielka was regarded as a potential regular for England given his performances at centre-back for Everton.
But towards the end of last season the 27-year-old ruptured his anterior cruciate ligament, and despite a successful operation, he required further surgery in November when he suffered a small cartilage tear.
After exactly 10 months on the sidelines, the former Sheffield United defender finally returned to action in February, and has since started and played the full 90 minutes of Everton's last nine matches, including Sunday's 2-1 win over Fulham at Goodison Park.
It has prompted speculation Jagielka will be in the England squad as back-up to Rio Ferdinand and John Terry in South Africa.
If not, Jagielka knows he can look forward to putting his feet up to complete his rehabilitation before throwing himself into next season.
"I'm not sure what's going to go on this close season, although I think I'm in a win-win situation - with one a bit more win than the other," said Jagielka.
"If I'm on a plane to South Africa it will be amazing, if not then it will be a nice little break for me.
"I've spoken to the (Everton) physio and we've had a laugh and a joke about it, and it's hard to make a decision.
"But as far as I'm concerned I'm available to go this summer. I'm sure the physio, with his Everton head on, will not want me to go.
"But for England and for me, he'll be delighted if I get the chance to board the plane.
"If I did get called up I couldn't turn it down because I don't know if the chance would ever come up again.
"I've always played with my heart rather than my head, and I'll continue to do so if the physio lets me."
Although Jagielka has been given no indication as to whether he is in Capello's thoughts at present, he feels he is in with a chance.
"You think about getting a couple of caps, but if the possibility arises of playing in a tournament like the World Cup, it's a once-in-a-lifetime opportunity for someone like me," added Jagielka.
"I'd be delighted to go as a squad member. The two first-choice centre-halves are pretty much nailed on, but the next two are up in the air, and from my point of view I'm delighted that's the case."
Although Jagielka would love to be part of Capello's plans, he also knows a summer off would serve him well for the future.
"My knees are still a little sore," said Jagielka.
"I jarred them both in the game, which isn't ideal, but it's something I'm going to have to get used to.
"I used to be made of rubber, but now there are a few more bolts in there!"
Asked if he had needed to adjust his game to compensate, Jagielka added: "I don't feel that way, but in some respects I don't feel as sharp as I did at some points last season.
"Whether that's because I've been out for 10 months or whether I've a new knee, it's hard to judge.
"But I'm really happy to be back, which I think you can see with my mannerisms and stuff, and the results haven't been too bad. It keeps a smile on your face."