I got modafinil directly, I didn't talk to a doctor about it. You can quite easily purchase it on the Internet, it is basically an unregulated market.
If you wanted to do things through a legit medical forum, the clinical use of modafinil is for shit work or for people struggling with sleep. This would probably be the angle to approach it, but it depends on your relationship with the doctor etc.
You may be interested in this, I have found a concoction of Caffeine (60mg), taurine and L. Theanine mixed with vitamin C is a fantastic mix for a more subtle boost to daily productivity and general clarity. Modafinil is more potent, but I enjoy more the subtle effects these capsules are giving me.
Either substance may or may not suit you personally, but if you're interested I would recommend trying them. I would be more hesitant to recommend modafinil but if you are wise with dosage it may be what you are looking for.