“If I could, I would stop the passage of time. But hour follows on hour, minute on minute, each second robbing me of a morsel of myself for the nothing of tomorrow. I shall never experience this moment again.”

Letter to Abraham Lincoln on his Gettysburg Address (20 November 1863).

Source: This Lullaby

Source: Hell

A Language Older Than Words (2000)

As quoted in The Wilson Era; Years of War and After, 1917–1923 (1946) by Josephus Daniels, p. 624. Referenced in "Bartleby.com" http://www.bartleby.com/73/1288.html
1920s and later

Edie describing a low point in her relationship with Bob Neuwirth
Edie : American Girl (1982)
Context: It was really sad - Bobby's and my affair. The only true, passionate, and lasting love scene, and I practically ended up in the psychopathic ward. I had really learned about sex from him, making love, loving, giving. It just completely blew my mind - it drove me a little insane. I was like a sex slave to this man. I could make love for forty-eight hours, forty-eight hours, without getting tired. But the minute he left me alone, I felt so empty and lost that I would start popping pills. He had more or less quit using drugs... When I first knew him, a friend of his used to come up with him to my apartment and they'd do a number in the bathroom. This guy eventually died of a heroin overdose, and Bobby left drugs alone after that. But if I wasn't practically in the act of lovemaking, I would be thinking of how to get hold of drugs. I really loved this man.... What happened was that Bobby said, "Let's go to a party. They're making an underground movie," and he said that I, the Warhol heiress, queen, star, socialite, blah, should be there. Bobby really wanted to go. I had a bad scene with him. I pulled out a knife and I wasn't going to let him out the door until he made love to me. I always get really dreadful. But we finally went. I went through it all. I was furious - this after about two years of our continuing relationship. Finally I said, "Now I'm going to leave this party. I'm fed up." He said that was all right: he'd met all the people he wanted to meet, and he'd watched the film begin shot. So we got into my limousine and he said, "Where would you like to eat?" I thought I was going to explode. Where would I like to eat? I screeched at him, "Why the hell can't you make up your own mind where we're going to eat? Why do I have to make all the decisions?" I was just livid, out of hand. I got madder and madder as we drove along, and just as we drove by the Chelsea Hotel I did something. I've never done anything to hurt anyone, and yet I was so furious that I pressed the button and rolled down the window screen - the glass plate between the front and back seats - and I told the chauffeur that the man in the back was molesting me; he was a junkie! I was so horrified by what I'd said, so flipped out by that, that I jumped out of the car into the path of the oncoming traffic, certain that my head would be crushed. All that happened was the I got bruised, badly bruised, but no broken bones. I mean, I was conscious, not destroyed at all. But I'd done such a terrible thing! I couldn't reconcile that. I had been about to explode. The hotel people came out, and they and Bobby carried me in. I had to pretend I was unconscious because I couldn't comprehend the fact that I had tried to get him busted, to hurt him seriously. He was the only person I had ever gotten violent about. I take out whatever violence comes into my system much more heavily on myself than on anyone else. But that was a pretty tight squeeze. I really craved making love to him.

There is no indication that Einstein said this. According to Quote Investigator, the earliest publication of a quote similar was in a collection of articles about manufacturing in 1966, when an employee of the Stainless Processing Company wrote a piece titled "The Manufacturing Manager's Skills." The article attributed the quote to an unnamed professor at Yale, by saying, "If I had only one hour to solve a problem, I would spend up to two-thirds of that hour in attempting to define what the problem is." (See, 1966, The Manufacturing Man and His Job by Robert E. Finley and Henry R. Ziobro, "The Manufacturing Manager's Skills" by William H. Markle (Vice President, Stainless Processing Company, Chicago, Illinois), Start Page 15, Quote Page 18, Published by American Management Association, Inc., New York. Verified on paper). https://quoteinvestigator.com/2014/05/22/solve/
Disputed
Variant: If I had an hour to solve a problem I'd spend 55 minutes thinking about the problem and 5 minutes thinking about solutions.

3 December, 2015
As President, 2015
Source: 20 Minutos http://www.20minutos.es/noticia/2620020/0/mariano-rajoy/bertin-osborne/frases-entrevista/

Source: City (1952), Chapter 7, “Aesop” (p. 207)