A lot of the time, meditation is no fun at all: you're tense, uncomfortable, distracted, and bored. You can't stay focussed on the meditation long enough to actually do it, so how could you be benefitting from it? And rather than cultivating focus, or peace, or compassion, you seem to be cultivating irritation and a lack of motivation. Is it worth sitting here doing this at all?
Meditation teachers will sometimes say that this kind of meditation is just as good as any other, and that thinking in terms of good vs bad meditations is a symptom of your delusion, etc etc. And while probably that's true in some profound spiritual sense, the reality is that: a) we all like some meditations better than others, and focussed, calm ones have distinct advantages, but also b) the "bad" ones really can be equally useful. Here's how.
When you are having a difficult meditation, you have an opportunity to train yourself to relate in a helpful way to difficulty. Because this meditation isn't the only difficult thing that you'll face in life. There will be times when doing your job is difficult, boring, and unpleasant, and the same will be true of time spent with your family, time spent doing housework, and most other things you do. So, how do you respond to difficulty in those situations? Well, you probably respond in the same way as you respond to difficulty in meditation. Perhaps you try harder, berating yourself for doing a bad job. Or perhaps you stop trying, and turn in a half-hearted effort. Or perhaps you just give up - you quit the job, or avoid your family, or never do any housework.
But what could you do, if you were to respond in the best possible way? If you really wanted to get the best out of the situation, what sort of attitude to it would you need? Well, that's what you'll discover in meditation. Because, provided you don't actually stop, you will have to come to terms with your mind; to find an attitude that works. And then you might find yourself taking the same kind of attitude to other difficult situations, whether in your work life, your home life, or anywhere else.
My prediction is that a driven, self-critical attitude won't work particularly well - mental agitation makes it harder to focus on your meditation, so more effort might not lead to better concentration. And even if it does, you won't be able to keep it up for long. And even if you can keep it up for the rest of this meditation session, you'll have made the whole experience so unpleasant for yourself that you won't feel much like doing it again the next day. On the other hand, giving up and making no effort won't work either.
What does work, I humbly submit, is an attitude of gentleness and patience, but also persistence. You need to keep on going, no matter how many times the mind wanders, and that will be much easier to do if you are gentle with yourself, and patient with the process. With this kind of attitude, you can keep on going, day in, day out, through good moods and bad, through “better” meditations and “worse” ones. Little by little, you can build your mindfulness, while also building your capacity for gentle, patient, persistence, in the face of a never-ending challenge. And perhaps you’ll find yourself drawing on that capacity elsewhere in your life: perhaps you’ll find you have a new way of facing challenges, and pursuing goals.