The young actor begins on the floor of his sunless apartment in the Bronx and does up to 100 midmorning pushups to the sound of a metronome, his strapping arms pumping a puddle of sweat around his hands. He concentrates. The Seventh Avenue subways rumble and squeal to a stop periodically in the background, on the elevated portion of their run to the Bronx.

For Damien Leake, 31, the days are mostly for keeping his body in shape and his actor's inner eye keen. A physical actor, he wants to be ready for the next call from the theaters from Broadway to Denver that give him his work.

"I don't get considered for certain roles," he says. "Largely I am cast as a tender, sensitive . . . half-crazed killer." A laugh rattles from within his chest. "A killer of men," he laughs again, showing dimples, but not because it's funny.

He was in "Death Wish" (a mugger and early victim of Charles Bronson's vengeance), "Serpico" (the rapist beaten senseless by the cops) and "Apocalypse Now" (a wild-eyed machine gunner). Tonight (Channel 26 at 9) he will star in the PBS premiere of "The Killing Floor," a drama based on the struggle to organize Chicago's stockyard workers after World War I.

He is asked why he doesn't get more varied work.

"I don't come to auditions apologizing for what I am and what I can do," he says. "In my mind I am a black man. I come on as a black man. A force to be reckoned with, and in that sense I am threatening."

Leake, a graduate of the storied New York High School of the Performing Arts, has seen his career through dizzying highs and sobering lows, but he never thought that after 15 years he'd be back in the Bronx, where he grew up. He didn't think he'd be on the eve of sharing parenthood with the woman he has lived with for the last three years, dancer Diane Hayes, worrying about how he will feed his first child, expected in June.

But then, he never thought he'd make a living as an actor.

Most actors with his talent would spend evenings dreaming of stardom. Instead Leake, a self-taught pianist and self-described hell-raiser, is writing musicals into the night.

He says that for most serious black actors becoming a "star," in the way that young Richard Geres or Kevin Klines pop up and form the newest ranks of bankable talent, "is not even a remote possibility."

His aim, he says, is to work regularly at his trade.

"I've never seen an actor do something that I didn't think I could do. In my heart of hearts, I believe that. I don't think every actor can make that statement," Leake says.

"I feel like a carpenter, or a plumber. But when people need some carpentry or plumbing done-- they go out and hire a shoe salesman. People need some carpentry done and they say, 'Okay, go get Mr. T or O.J. Simpson' . . .

"I would like to play different kinds of roles, roles that white actors are up for. But they have to go to white people--let's face it. You can't get the girl, that's out. Unless, of course, the girl is black, then you can get her. But white people don't want to see that. Then it's a black movie."

Leake began working professionally during his last year at Performing Arts in 1970 and quickly joined the downtown theater world, a subway ride away from the home his father, a bus driver and unpublished author, built over 30 years ago in the once open farmland of the northeast Bronx.

Leake worked with and was nurtured by black theater professionals like arranger Chapman Roberts, actor Sherman Hemsley (of "The Jeffersons") and black theater impresario Vinnette Carroll ("Your Arms Too Short to Box With God"). White entertainment professionals, like nightclub performer Laura Kenyon, also befriended the newcomer.

Their pictures, and many more, line the walls of a room. There are also pictures of the parts he played--for example, "Carlisle," the psychopathic mainspring of the play "Streamers," with his shambling gait and switchblade. When Leake starred in the role at Washington's Arena Stage in 1976, it was the beginning of what he calls the best two years of his life. He also worked with Al Pacino twice in those years, first in "Serpico" and then on Broadway in "The Basic Training of Pavlo Hummel."

The best years included 15 months of self-imposed celibacy, which the actor said was also good.

"Sometime in Toronto, in the middle of playing "Carlisle," "I felt like I needed to get control of myself."

He moved from the Bronx to a spacious house overlooking Manhattan, high on the New Jersey palisades. It was filled with theater people, sunlit window seats and music. He learned how to script music for his tunes, songs for his musical, "Child of the Sun." Friends, including some of New York's finest black performing talents like singer Armelia McQueen ("Ain't Misbehavin' "), came to the house to perform his work in his living room.

Near the end of 1980 he became the first recipient of the Richard Rodgers Award, $60,000 from the composer's widow to stage his musical.

It was, he says, the beginning of the worst year of his life.

"When I heard I got the money it was terrific. I was gonna make this thing for everybody who hadn't worked, because nobody was working at the time. I mean everybody I knew wasn't working," Leake recalls.

But suddenly a show called "Dreamgirls" took his first choices for "Child of the Sun"--"fabulous talents, but they were working in the chorus because they needed the money."

He learned he would have little control over production and direction "It was a mass education," he says. "I learned more in three months than I did in the whole 20 years prior."

He found himself working as rehearsal pianist for his own show, only partially paid, and driving a cab because there were no theater jobs. It was like a bit part in a B-movie about an actor's life, so he played it, right down to the running poker game with fellow cabbies.

"I was largely living on playing poker," he says. "I made more money playing poker than driving, I almost feel bad about it. But it was a question of doing what you had to do."

"Child of the Sun," which follows a cycle of hope and disappointment through three generations of a black family, ran for three weeks at New York's Henry Street Theater, off-off-Broadway. The New York Times liked the music, but not the book.

Because of a dispute over the play, he no longer speaks to his youngest sister, now dancing on Broadway. His acting work dried up for a while, until the television drama "Nurse" needed a sensitive but volatile bank robber. When his lease lapsed, he moved to the Bronx.

But he has been working again: Francis Ford Coppola's "Cotton Club" (to be released later this year). "Of Mice and Men" in Hartford in January. He is rewriting "Child of the Sun" and two new shows. He coaches five young singers from the streets of Brooklyn who ride to the Bronx to work with him.

"I cannot explain to you what a terrific feeling seeing 'Child of the Sun' was on stage. I cried. I cried every night to watch all of these people working because of something that happened to me."