Lyric discussion by anna.sthetic 

Cover art for Push lyrics by Marianas Trench

Well at first thought it sounds like it's about sex...but I guess if you really analyze it, it COULD be about heroin...

"It'll wear you down and wear you down (You chase it breathing in and out and in and out)" -The 'wear you down' part is self-explanitory...the breathing in and out could be inhaling and exhaling...since he smoked the heroin.

"You didn't think you'd feel it all but you were wrong about it" -I guess that could be ...he didn't think that it would really have an affect on him but it did...like whether he thought he wouldn't get high and he did or maybe he thought he wouldn't feel shitty after and he did.

"Using like it's going out of style maybe just a little while This'll be the last time everytime's a last time" -I agree with mrsjoshramsay for this part...also the fact that he says "using" instead of "using it" or something makes me think it's more about drugs.