In your mid-30s to late 40s and feel like you'll never get promoted? You're far from alone, but you can take steps to jump-start your career.

FORTUNE -- Dear Annie: I hope this doesn't sound whiny, given the real economic hardships faced by people who don't have jobs at all, but I am so frustrated I could scream. I joined my current employer eight years ago, at age 27, with a fantastic track record as a salesperson, and did so well in my first two years here that I was promoted into middle management (regional sales manager, in charge of a 300-person team in 12 states).

And here I sit. Even though I've increased my group's revenues by double digits for each of the past five years (despite the recession) and all my performance reviews have been great, I don't expect to be promoted again anytime soon, if ever. Why not? Because my boss is only about 50 and she's probably never leaving; and her boss is 59 and has said many times that he's not retiring until he's 70. So I seem to have two choices: Quit a company I really like working for, in order to move up somewhere else; or just accept the fact that there's no room at the top and stick it out here. Your thoughts, please? — Just Marking Time

Dear J.M.T.: Ah. You, my friend, have run smack into what is sometimes called in HR circles the "gray ceiling" -- a vast crowd of Baby Boomers who are occupying millions of plum senior-level jobs. Almost 80 million strong, this generation was supposed to be retiring in droves right about now, opening up lots of opportunities for Gen X up-and-comers like yourself.

Unfortunately for you (and the roughly 50 million other Gen Xers in the U.S.), that isn't happening. Blame the recession, at least in part: The downturn, including the collapse of real estate values, rocked Boomers' sense of financial security, causing some to delay retirement for at least a few more years and others to put it off indefinitely. More