No great surprises there really.... glad you enjoyed it! I clearly remember the first time I tried speed, back in 1975. A wonderful, glorious high, one of those peak moments, my first taste of a 'strong drug'. And, quite naturally, just like you I wanted it to go on forever and ever... and saw no reason why it shouldn't. Alas, my naivety and inexperience at 16/7 were in full bloom, and I was still idealistic, supremely positive, and believed anything was possible with determination, hard work and a bit of luck.
It goes without saying that this joyful enthusiasm, faith and hopefulness soon gave way to cynicism, disappointment, expectation of failure and negativity as life took hold. This was not due to drugs, in fact they renewed my joy, hope and joyful wonder several times, and have continued to do so all my life. I soon had to face the fact that, no matter how simple, desirable and wonderful it seemed to be to continue that marvellous speed rush forever and ever, it was impossible - no matter how much whizz I begged, borrowed, bought, stole or manufactured. And I learned a vital lesson concerning the nature of the Universe and the human condition - "Nothing Good Lasts Forever". Followed by - "You Never Get Something For Nothing", which particularly applies to physics, chemistry, and biology.
That delicious, ecstatic, divinely joyful speedy state is impossible to extend indefinitely, no matter how much you take and have available. The way it works depends on amphetamine's effect on the body and brain, releasing hormones and chemicals which actually produce the sensations of 'joy and energy' in the brain and nervous system. Unfortunately, there are only limited reserves of these substances, and once depleted and used up, no amount of speed will have an effect, as it takes the body an infuriatingly long time to manufacture fresh supplies of them. You can try bigger doses of course, I know I did, as do most people, but there's no way out - you just have to wait and be patient.
Whatever you take or do, evryone's body requires sleep in the end, to repair, replenish and recover. You can put it off for a long, long time, but if you keep going too long, you will get very ill, confused and depressed. It's a bit like having a leaky old car... you can keep filling the tank to brimming, keep the throttle wide open, and it will go, fast and well... until the tyres go flat, or oil and water run out, at which point no amount of petrol will make it go.... and it will be terminally damaged if you keep going.
I hope that doesn't sound too patronising.... or depressing? That's just the way it goes I'm afraid.... the way of the world. Don't despair though, I'm sure you will experience more of these marvellous moments, and it seems you are already thinking about ways of doing it? The thing is, there really are no stimulant drugs that compare with amphetamines, nothing is stronger or has that 'rush'. Another 'Golden Rule' which applies to drugs and drug experiences, says that "Less Is More!". This especially applies to stimulants and is absolutely vital when experimenting with psychedelics. With stimulants, you will need to take bigger and bigger doses to get a satisfactory effect, which wastes not only money, but brain cells in the end. Psychedelics require even more 'discipline' and patience however, as they can provide some of the most incredible, wonderful and exquisitely joyful moments of one's whole life (IMHO), but only if carefully rationed and respected. THey will fail to work at ALL if overused , and most need a week to recover from before working properly. You just cannot 'stay on the ceiling' forever....