If you regularly exercise in the style of 3 sets of 12, 15, or 20 exercises, you’ll be familiar with your brain going off course while your body is going through the motions of the 3 sets just as it got into the flow / rhythm of the exercise sequence. Somewhere around halfway you suddenly realise that you’ve lost count and are now in a quandary about whether you’re on the 2nd or 3rd set – let alone which repetition you’re just doing at the time of having realised that you’ve lost count!  How can you prevent this?Â
 Easily!  Before you go for the next workout I recommend that you reasonably reliably learn to count to 20 [that way you’ve covered the number of possible repetitions whether they be 12, 15, or 20] in 3 foreign languages. During your next workout use 1 language for 1 set and you’ll see how sharp your brain will remain on the counting!  The fact that you’re counting in a foreign language will force your brain to concentrate on the counts. If you use counting in foreign languages that you already speak, your counting will be more automatic than will be counting in a foreign language that you’ve just picked up from Google Translate for the fun of it. But regardless of how automatic your counting be, your brain will still be forced to concentrate on the counts and thus won’t go off the course of your focus! If you find fun in challenging yourself, then learn the counts in foreign languages you do not already speak.  That way you’ll be less automatic, thus forced to concentrate even more on the next count, and may even find fun in seeing how quickly you can think of the next count word and whether you can master the sequence of the count words more smoothly…  After all, it’s a workout, right?:)
If you try and like this, you can get even more creative. Learn the counts in 3 more foreign languages [the less related to those you already speak, the better] and you’ll now have a stock of the counts to 20 in 6 foreign lingos.  Always vary the order of the languages. But if you have only 3 languages in stock, you’ll be limited to only 3 combinations of variation.  But if you have 6, you have more choices to play with.  Again, it’s a workout, right?:)