Gym/working out.. i havn't been to the gym in about 12 months im quite skinny and have like the skinny 6pak..?

[Alex Barrett]

but i went back to the gym about a week ago and have done like 2 proper work outs since and i have noticed a huge difference in only 2 work outs is this normal? it's like a bigger difference in 2work outs than the difference i made in about 3 months of working out a year ago? .. why is this? # (when i say big difference i mean 6pack looks alot more toned arms bulked out and are even looking shaped and them side things on my back/sides even looking good?

thanks
19, thanks for your advice