A few months ago I started using Anki to fill the massive hole in my knowledge of German vocabulary. I've since studied more than 1600 flashcards and it's helped me immensely. Anki will automatically space out repetitions of the cards for you depending how difficult or easy you found them. This is called spaced repetition and is an evidence based way to remember things in the long term. Just make sure to force yourself to do it every day.
https://apps.ankiweb.net/ It's free and open source
For German learners, here is the deck that's helped me the most: https://ankiweb.net/shared/info/653061995
4000 words may seem like a lot but it's worth it. Every word has an example sentence, audio sample, as well as plural forms if a noun and for the verbs some conjugated forms and simple past and past participle.
also it's good for remembering other shit too. med students use it religiously
Yeah, totally. Another reason I stopped is because I have a nasty tendency to drop something if I'm not sure it's working; I do it with physical exercise and guitar practice routines too. After the initial quick gains I become dissillusioned, and I get anxious thinking about my end game, and how I can develop the exercise to make it harder or more effective, and I give it up- sometimes without doing anything in its place!
A really good piece of advice I heard from the weight lifting world is to "trust the process". Even if you're not sure it's working, keep on doing it; odds are you're still progressing, just slower.
I'll get back into Anki now, anyway. Thanks for the motivation!