You do realise that you're doing something quite dangerous by turning to dopamine-influencing drugs to motivate you, right? This class of drugs can change brain structure, promote cancer growth and generally make you devoid of emotion. At the very least, protect yourself with anti-oxidants and NMDA antagonists. There are plenty of less serious things you can take/do if you simply lack motivation. Exercise, cut out sugar and caffeine entirely and try Noopept.
I've been on Ritalin since I was 10. I used to take it daily, now I just take it when I need to concentrate for extended periods of time. Thank you for your concern, though.
Nothing at all like that. I was prescribed it for ADHD as a child. Now, I take it if I'm cramming or spending all night in the lab. Generally, less than once a week.