I think the need to play long notes every day, and scales too - especially over the break - really, is the hardest thing about the clarinet. It's like there's this "work" you have to do every day before you get to the fun stuff. On a guitar, or a piano, you may get sore fingers if you don't play for a while, but at least you can still play. Neglect the basics on a clarinet and you lose the ability to play with any degree of nice sound. So somehow you have to accept ten or fifteen minutes work every day is just part of the territory. Once you've made that choice, then there's a word of pleasure to be had. The true secret is to find ways of making these drills not boring - I'll play very long notes (say 20 seconds or more) whilst working on a scale (thereby killing two birds with one stone) and really listen to the tone and the notes and do this for ten minutes. I'll play long notes throughout the range. Around the throat register. The chromatic scale with long notes (say 5 - 10 seconds). Blues scales - major and minor. Patterns. Loads of things to practice slowly and afterwards you're ready to have fun...
And that's the problem, I don't always have the option of practising every day, and sometimes, I just don't feel like it.