There is no such thing as a bad meditation. If all you can do is stop and breathe three times then that is better than that not stopping at all.
A two minutes seated meditation is better than breathing in and out three times. A five minute meditation is better than a two minute meditation. A ten minute meditation is better than a five minute meditation.
A 15 minute meditation is better than a 10 minute meditation. A 20 minute meditation is better than a 15 minute meditation. A 30 minute meditation is better than a 20 minute meditation.
A 40 minute meditation is plenty. Only very rarely should you meditate longer than 40 minutes. If necessary, meditate for 40 minutes, then have 10 minutes of walking meditation, then meditate for another 40 minutes.
Some people report that they can do walking meditation when they cannot do sitting meditation. Walking Meditation is great. It is much better than no meditation.
If you sit down to meditate and sneeze five times, get up to go to the bathroom three times, blow your nose six times; adjust your position 25 times; think how much you hate your parents, spouse, children, boss, friends; plan to buy a family size pizza with triple cheese as soon as you come out of meditation; plan to buy a pint of chocolate chip ice cream as soon as you come out of meditation, plan a trip to South Africa, break down and check your calendar or your email during meditation – all of this is better than no meditation at all.
As long as you sit back down and resume breathing, repeating a mantra, or watching your mind, as often as you can, then that is better than not meditating at all.
I mean the above literally, but I am also trying to trick you into sitting down and meditating. My experience is that if I can sit down for 10 or 15 minutes, my mind will calm down. It’s just a question of tricking myself into sitting down.
Set your expectations as low as possible. Sitting down and having the world’s worst meditation is better than having no meditation.