When it comes to learning a language it’s important to talk about consistency.
Learning a language is a lot like going to the gym. We can’t go there once an expect to be healthy. A few times a year? better but still not quite enough.
In order for us to improve we need to be putting the work in on a regular basis. This doesn’t mean we have to be studying every hour of the day. Just like exercise, if we work our brains all the time without rest then we won’t get better, in fact we may get worse!
What we need to do is put in regular amounts of practise, even if it’s in small amounts and we will be able to see improvement in our language ability.
Again like going to the gym it is much better to do small amount on a regular basis that one huge amount on a rare occasion.
So don’t worry about how much effort you can put into your study / practise today, as long as it’s something (no matter how small) then it will help. Also, the more often we do these things, the more likely they are to become longer term habits.