How to get myself to practice my instrument?

In March I finally bought myself a bass and got to play right away. I practiced almost daily for at least 3 weeks. And then, like always, something messed up my routine and eversince, I exercised maybe 2-3 times a month.

Everytime I pick it up again, I have so much fun and am so proud that I made myself practice! But then again, I kind of forget that it's even there eventhough I placed the damn thing in the middle of my room. And when I'm sooo close to playing either my fingernails are too long, so I have to clip them or my iPad's battery is down... so momentum's gone and I go to bed without having played. It's just the same thing everytime.

I really want to increase the times I play. It got better since I began to take Concerta again in November but I'm still not at the point, where I want to practice at least 2-3 times a week.

Has anyone experience similar and maybe knows how to build up a *lasting* routine?

TL;DR: I want to practice playing bass at least 2-3 times a week but can't get myself to do it. Any advice on building a lasting routine?