Some good advice given by Ajaan Fuang in "Awareness Itself":
§ "When the meditation goes well, don't get excited. When it doesn't
go well, don't get depressed. Simply be observant to see why it's
good, why it's bad. If you can be observant like this, it won't be
long before your meditation becomes a skill."
§ "Everything depends on your powers of observation. If they're crude
and sloppy, you'll get nothing but crude and sloppy results. And your
meditation will have no hope of making progress.
And also others:
§ A young nurse practiced meditation with Ajaan Fuang several days
running, and finally asked him one day, "Why wasn't today's session as
good as yesterday's?"
He answered: "Meditating is like wearing clothes. Today you wear
white, tomorrow red, yellow, blue, whatever. You have to keep
changing. You can't wear the same set of clothes all the time. So
whatever color you're wearing, just be aware of it. Don't get
depressed or excited about it."
§ A few months later the same nurse was sitting in meditation when a
sense of peace and clarity in her mind became so intense that she felt
she would never have a bad mood infiltrate her mind again. But sure
enough, bad moods eventually came back as before. When she mentioned
this to Ajaan Fuang, he said, "Looking after the mind is like raising
a child. There will have to be bad days along with the good. If you
want only the good, you're in for trouble. So you have to play
neutral: Don't fall in with the good or the bad."
§ A student came to complain to Ajaan Fuang that she had been
meditating for years, and still hadn't gotten anything out of it. His
immediate response: "You don't meditate to 'get' anything. You
meditate to let go."
§ The seamstress, after practicing meditation with Ajaan Fuang for
several months, told him that her mind seemed more of a mess than it
was before she began meditating. "Of course it does," he told her.
"It's like your house. If you polish the floor every day, you won't be
able to stand the least little bit of dust on it. The cleaner the
house, the more easily you'll see the dirt. If you don't keep
polishing the mind, you can let it go out and sleep in the mud without
any qualms at all. But once you get it to sleep on a polished floor,
then if there's even a speck of dust, you'll have to sweep it away.
You won't be able to stand the mess."
§ "Persistence in the practice is a matter of the mind, and not of
your posture. In other words, whatever you do, keep your mindfulness
constant and don't let it lapse. No matter what your activity, make
sure the mind sticks with its meditation work."
§ "Meditating isn't a
matter of making the mind empty, you know. The mind has to have work
to do. If you make it empty, then anything — good or bad — can pop
into it. It's like leaving the front door to your home open. Anything
at all can come strolling right in."