The 34-year-old, who has played 23 tests since his debut in 2011, was one of a couple of surprise inclusions in the Australia squad named on Friday for next week's opener against England in Brisbane. [nL3N1NM5YE]
Marsh secured his eighth recall to the test side with some solid form for Western Australia but conceded that failure on Australian cricket's biggest stage could end his test career.
"I'm not trying to think about it that way, it's another opportunity for me to get out there and play some good cricket for Australia," Marsh, who averages 36 in tests, told reporters in Brisbane.
"I know I've got some runs in me still to go, so I've just got to prepare well and just enjoy it, have a lot of fun and bat myself in."
Marsh has been opening for his state but is likely to bat in the number six spot against England having seen off the claims of brother Mitchell, team mate Hilton Cartwright and the incumbent Glenn Maxwell.
After playing in all four tests on the tour of India earlier this year Marsh was dumped for the following tour of Bangladesh in what was quite a blow given he was considered something of subcontinent specialist.
His recall did not cause as much surprise at that of 32-year-old wicketkeeper Tim Paine, a pick criticised as "confused" by spin bowling great Shane Warne, and Marsh himself was left with just one prevailing emotion. [nL3N1NN2EZ]
"It's just excitement," Marsh added. "I hadn't really thought about it much over the last two or three of months. I just thought if I played good cricket for WA then I might have a sniff. I just can't wait to get out there and have a crack.
"An Ashes series in Australia, it doesn't get any better than that, I'm going to give it a red hot crack."
Injury has also played a significant role in Marsh's stop-start career but he said he was in good shape going into the five-match series.
"My body's in really good condition at the moment," he said. "I feel like I'm hitting the ball the best I have done for a long while so I'll go in with plenty of confidence."
(Reporting by Nick Mulvenney, editing by Peter Rutherford)
