Yes, it will be rough goings for at least the first week.
Ugh, I took too long reading the rest of the replies on this page before responding to him, so now I have to quote you to tell him to ignore what you just said!
Being in your 30s means slower quick-twitch reactions as well as fewer COD-style games played at that age compared to teens. Teens not only primarily play these types of games, but also have more time to commit to them, whereas a 30-year-old plays other types of games now and has less free time to master them.
Well I'm 36 and I played CoD since the first one. Before that I played a lot of Medal of Honor: Allied Assault.
Both MOHAA and Call of Duty on PC. I moved to Cod 2 and later CoD 3, both on XBOX 360.
Played Modern Warfare on PC, WaW on PS3, MW2, 3, Black Ops 1 and 2, Ghosts and AW all on PC.
Except I didn't really "play" Ghosts, because it was an unoptimised sack of shit that didn't even run properly on a i7 with 16gb of RAM and a R9 290......
Moved to AW on XBONE, got bored.
So all in all, I'm in my 30's with 12 years of CoD experience. Hell, even I fail hard at tims. But CoD is the most accessable shooter there is. I told many to try it. Some aren't playing for more than a few weeks and they manage to do pretty damn well.
On the consoles it's more accessable than PC because of the aim assist. On PC your aiming is more important and therefore harder to master.
It's not age, but just getting used to the pacing. Doesn't matter if you're 18 or 35.
It's not like Battlefield where you get pummeled from all angles without even catching a glimpse of your foe. Or you end up running around getting 0 kills in.
CoD is more over the top, fast gameplay. Anyone who isn't blind as a bat should get at least a couple of kills every match.