The midfielder returned as fit as he'd ever been for pre-season last time around after knuckling down last summer.
And the work eventually paid off. Jacko was recalled from a loan spell at Coventry City to make his Premiership debut at Portsmouth on Boxing Day and eventually made 14 appearances in the second half of the season.
"I had a week of complete rest, took my mind off things but I know the work I put in last pre-season set me up," said the 21-year-old.
"You have to come back and have that edge, especially with a new boss around. There will be changes, a new gaffer and we'll all look to impress in pre-season.
"He'll have his own opinions and you have to work your way into his plans for the season. I can play down the left side, so that's in my favour because there are so few left-footed players about.
"Hopefully there will be more to come from me next season."
Johnnie Jackson has been clocking up the miles again this summer having reaped the benefits of a similar programme last year.