Dealing with pleasant thoughts can sometimes be just as difficult as dealing with unpleasant ones. After all, happy thoughts often portray a future that's better than the present, which creates a longing in you. While longing might not feel like suffering, it certainly is.
In order to deal with happy thoughts - the ones that keep you up at night because you can't wait for the next day to come - you must treat them like any other thought forms that enter the mind.
You deal with pleasant thoughts the same way as you’d deal with unpleasant thoughts.
Notice them, but don’t follow them. Observe them come into your mind, but don’t get attached to them. As quickly as they come, let them go. Doing this will get you in the habit of relaxing behind any feeling of “too happy” or “too sad.”
Thoughts (and the emotions that follow) arise in two ways: either you consciously create them (if I tell you to think of a pink dog, you see a pink dog), or they arise on their own.
Ultimately, we want to limit the thoughts that arise on their own as much as possible, since they only make us suffer.
If you’re not the one creating the thoughts, then stop believing them.
When you can't sleep because you're so excited for tomorrow, your thoughts are sabotaging you. Intellectually, you know that you need to sleep so that you can enjoy tomorrow. So why does your mind not shut up and let you sleep?
The same reason it doesn't shut up any other time. Because it's regurgitating all the experiences you stored in there from your childhood until today, and then telling you how the universe needs to unfold in order for you to be okay.
The problem is, the only data it contains is your experience, not the wisdom of billions of years of creation. In other words, our minds don't know what they're talking about.
Stop giving the thoughts so much credit. Just witness them, no matter how exciting they may be, and do nothing more with them.
While doing this, you’ll constantly realize that minutes will go by, and you’ve been stuck on a single thought that has taken you to dozens more. That’s okay. Go back to noticing.
The more you let the thoughts come and go, the sooner you'll wake up in the morning, feeling rested, ready to enjoy the day.
Live with substance!