Greetings,
Wanted to write a brief report as I've searched for this info in the past and found it hard to come by.

First of all, tolerance - yes, it exists. It also builds very fast if you take your dose every day. However, it also goes away quickly. If you take it even just every other day, your tolerance will remain at a level that feels really good and like it won't ever get worse.

But sometimes you have days you can't skip your dose on. When I've taken my dose yesterday, and want to take one today with the same effect, I take 20mg more (usually I take 40, 2*20mg pills every other day). If I need to take a dose tomorrow even after that however I only take the same dose, 60mg, and if yet again I can't skip tomorrow I increase to 80mg. You may be worried that this is dangerous, but it isn't. It will increase your blood pressure and heartrate like a stimulant does, but it's okay, I've gone on runs with this dose and did just fine.

Potentiation - There are only 4 things I can confidently say have any kind of effect. First, having an exciting day ahead of you, and listening to good music, and eating delicious food. This works because it increases (warms up basically) activity in the associated pleasure centers, making it easier to ride the wave. Second, getting little sleep, 6 hours or less, will make you feel awesome when you come up (not healthy though). This is because we experience euphoria, the kind like cocaine, specifically during the time interval when dopamine levels rise, and less sleep means less dopamine to start with and therefore a greater difference. The third thing is taking the pills on an empty stomach and all together instead of throughout the day. Once again, this is due to a higher impact per moment of time on the dopamine difference. Finally, the fourth actual potentiator in the classical sense, is kratom, but with a twist. The reason it works is due to kratom's inhibition of one of the P450 enzymes which break down dextroamphetamine. This means the dextro stays longer in your system. However, with that said, kratom's opioid effects overpower the stimulant rush at above 3.5 grams in my experience, so don't take more than that, or take it later in the day.

On this note, does kratom impact vyvanse tolerance? The answer is no, in fact I feel like it makes my vyvanse hit harder the following day. And are they safe to take together? Yes, so long as you keep the dose preferably below 7 grams, but over that isn't critical if you're young and healthy like me. Myself I use 4.5g to smooth out the "crash" (which is very smooth contrary to the name, vyvanse is awesome and lasts long) and on vyvanse off days.

Also, is it safe to drink coffee with vyvanse? Yes, it makes it feel even better, but it does impact your heartrate noticeably.

Effect - Vyvanse is fucking awesome. Tiredness? Sleepiness? Hunger? Obliterated, you are a war machine. Euphoria? People say it doesn't exist, they're liars, it absolutely does and it feels awesome. The onset (euphoria) lasts about 1.5h after the dose starts kicking in, then on top of that you get about 6 hours of feeling great and fresh, after that it comes down and you might start to feel an edge, but very slowly, you will feel productive even into the night.

Does it improve productivity, and how? Yes it does. ADHD is real, it's not too bad but it makes discipline noticeably more challenging. Vyvanse puts you into a rush, where cheap recreation like scrolling Instagram no longer feels as fun, and things with clear goals to be attained and a path forward feel really exciting.

If you are a student, or if you aren't, make sure to get yourself some vyvanse if you have adhd!