Good question.
Generally speaking, positive/happy thoughts are not what cause us trouble. They come and they go. We tend not to get hooked on them, as it were.
Another category is useful thoughts. These might include "I need to call my dentist to arrange an appointment", "My kitchen appears to be on fire, I'd better throw some water on it" or "I'm hungry - I think I'll make a meal". Again, these types of thoughts don't cause us too much trouble.
Then there's the thoughts that are rumination about the past and worries about the future. These thoughts are often loaded with judgment and can cause us a lot of misery.
All thoughts are just thoughts but we can discriminate between those that are harmless, those that are useful and those that cause us misery. It's the third category that, perhaps, we need to be most mindful about.
My life used to be dominated by negative thinking. It made my life a misery. That's no longer the case and that's entirely down to mindfulness. I still have negative, judgmental thoughts from time to time but they no longer bother me. Just as the problems in my life are pretty much the same old problems - I simply relate to them differently these days.
Which reminds me...
There is an old story about a farmer who came to see the local wise man because he had heard that the wise man was a great teacher. Like all of us, he had some problems in his life, and he thought the wise man might be able to help him straighten them out. He told the wise man that he was a farmer.
“I like farming,” he said, “but sometimes it doesn’t rain enough, and my crops fail. Last year we nearly starved. And sometimes it rains too much, so my yields aren’t what I’d like them to be.”
The wise man patiently listened to the man.
“I’m married, too,” said the man. “She’s a good wife…I love her, in fact. But sometimes she nags me too much. And sometimes I get tired of her.”
The wise man listened quietly.
“I have kids,” said the man. “Good kids, too…but sometimes they don’t show me enough respect. And sometimes…”
The man went on like this, laying out all his difficulties and worries. Finally he wound down and waited for the wise man to say the words that would put everything right for him.
Instead, the wise man said, “I can’t help you.”
“What do you mean?” said the man, astonished.
“Everybody’s got problems,” said the wise man. “In fact, we’ve all got eighty-three problems, each one of us. Eighty-three problems, and there’s nothing you can do about it. If you work really hard on one of them, maybe you can fix it – but if you do, another one will pop right into its place. For example, you’re going to lose your loved ones eventually. And you’re going to die some day. Now there’s a problem, and there’s nothing you, or I, or anyone else can do about it.”
The man became furious. “I thought you were a great teacher!” he shouted. “I thought you could help me! What good is your teaching, then?”
The wise man said, “Well, maybe it will help you with the eighty-fourth problem.”
“The eighty-fourth problem?” said the man. “What’s the eighty-fourth problem?”
Said the wise man, “You want to not have any problems.”
