The Cumbrian joined Rhinos three years ago, initially on trial, after Hull KR declined to give him a new deal.
Since then, despite being used regularly off the bench, he has quietly become a mainstay of the team.
The season which begins in two weeks’ time will be the former Bradford Bulls man’s 14th as a professional player and, though his contract runs until the end of 2023, he believes it could be a defining one.
Donaldson insisted “every year is a big one for me”, but stressed: “I feel like I am starting to get into the peak of my career at the moment.
“The last few years, I have built a nice foundation at Leeds and I want to really build on that and try and kick on from there.
“I’ll do whatever I can do to help the team; I am not a flashy player, I just do the small stuff and try to do it the best I can.
“Those small things make a big difference and that’s what I focus on - doing the little things right, bringing that energy and that impact off the bench when they need me.
“I want to keep improving, I’ll keep working hard off the field and hopefully that’ll show on it.”
Donaldson made his name as a second-rower, but could be used more at prop this year, particularly while Tom Holroyd is on the injury list.
He said: “I’ll play anywhere I am asked, anywhere in the pack - second-row, loose-forward, front-row.
“I think the game has changed a lot over the years and now loose-forwards play like front-rowers, or front-rowers play like loose-forwards.
“I am happy to come into the team wherever I am needed.
“I am off the bench most weeks and wherever Rich [Agar, Rhinos’ coach] needs me, I am happy to commit.
“I will give everything I can in that position.”
Donaldson played in the Boxing Day win over Wakefield Trinity, but picked up a two-game ban which was completed last weekend.
“It’s good to really build a decent foundation in the friendlies to take you into the season,” he said.
“Obviously I haven’t been able to do that, but I’ve been working hard off the field on small parts of my game.
“It has been pretty tough missing out on those games, because you haven’t really got a focus at the end of the week.
“I have really been focusing on my fitness and I am excited for Sunday, just to get back to it and get among it.”
The visit of Hull, in Tom Briscoe’s testimonial game, is Rhinos final rehearsal for their Super League round one clash with Warrington Wolves on Saturday, February 12.
Of Leeds’ 32-man senior squad, only Holroyd (ankle) and Sam Walters (shoulder) are unavailable because of injury, both suffered during a game.
Donaldson said: “I feel in great shape.
“We’ve had Rich Hunwicks come in and JT - the guy who’s running the weights program - and it has been a lot different to what I’ve been used to in the past.
“I think the professional level has gone up a notch and that’s really a part of our game that’s going to help us to go to the next level.
“I am really excited about that, it has added a new dimension to what we’ve been doing the past few years.
“I am feeling fit, feeling strong and excited to get out there and see how it feels.”
Hull will be the first full-strength, top-flight opponents faced by Rhinos’ new-look side, but Donaldson believes Leeds are “without a doubt” capable of challenging for silverware this year.
“We’ve taken steps in the right direction for the last few years,” he insisted.
“We are slowly building a team that’s going to compete at the top. I think it’s part of the plan to keep building and we’ve got depth in every position now.
“Everybody’s snapping at each other’s heels for their spot, which is going to bring the best out of each other.
“You can’t have a week off when you can think you’re safe, because you’re definitely not.
“You have to fight every week for your position in the team and you know if you do have a bad game someone else is going to take your spot.”
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