I've noticed that when I put in a lot of effort and study hard, and keep at it day after day, that I usually end up stopping for a long period of time. I mean, I will keep up my routine for a week or two, and then I won't do any studying for 3 or 4 months. I forced myself to work hard and then suddenly when I can't study one day or two days, I can't get myself back into my routine. The body and the mind just want to keep resting. The work I was doing built up a kind of reluctance to study. It was good while I did it, but my desire and motivation went out the window.
Because of those experiences, I realize that it is best not to make language learning a chore. You are more likely to stick to it as long as it retains its excitement. Therefor, you should definitely have language learning activities that are easy. The more the better, but I have only found listening to fit the requirement of being easy. If you feel like listening to a structured lesson, then by all means do so. Otherwise you can just listen to news, conversations, or monologues. Even if you are too tired from your day of work and don't feel like concentrating, just listen to an internet radio program (not music). Once in a while you will catch some words that you have studied, but the whole time the language will be entering your system through your ears.
I recommend you have some activities like this for those times when you don't feel like doing anything. You know you'll feel guilty if you do nothing for awhile. But if you at least spend some time listening, you can keep your mind fresh with the sounds of the language.