The right-arm quick was dropped for Australia's series finale against South Africa in Cape Town earlier this year in favour of James Pattinson and told to increase his pace by coach Darren Lehmann.
Rewarded with a call-up for the series opener versus Pakistan at the Dubai International Cricket Stadium, Siddle revealed his preparations had involved adding extra muscle and weight in an attempt to rediscover form and speed.
Having put on around five kilograms of muscle since returning from English county action with Nottinghamshire, the 29-year-old feels he is ready to hit the ground running in the two match series.
"It's probably helped me think about a few things I need to work on and change and get right," Siddle explained in reference to being dropped. "I think I'm back to where I want to be.
"I'd trained too hard and that, combined with the amount of cricket we were playing and the intensity we play at, probably did affect me.
"I had to change the training routine a little bit and I'm seeing the benefits at the moment. Hopefully they continue.
"I am still feeling as fit as I ever have. I think that stint in England where I was still playing has given me a good base and I have a lot of kilometres in the legs to keep ticking over."
Siddle also suggested his bulked-up physique and break from the game could serve him in much the same way as it did team-mate Mitchell Johnson, who missed the ICC World Twenty20 with an infected toe.
Having proven a thorn in the side for England during Australia's 5-0 Ashes win, Johnson missed the tournament in Bangladesh - something Siddle believes has proved a positive for him.
"He bowled for five years straight before he hurt his foot and he was down to bowling high 130s [kilometres per hour] or low 140s at that stage, for a bloke who bowls mid-150," Siddle continued.
"For him to have that break and freshen up mentally and physically and come back and bowling the best he has just shows, a bit of rest here and there, work on a few things, change a few things and [you can] get that rhythm back.
"I am feeling good and that's what it is all about."