So - in order for those statements to be relevant for you, there's a few tips I'll pass along.
1. Don't think that you know everything. Always look for more knowledge.
The "no-it-all" person is usually very negative underneath his or her assurances. There's also, most likely, a whole bunch of insecurity under the surface. Recognizing that you can always learn something else (and be open to that fact), means that you realize that life holds a whole bunch of mysteries just waiting to be discovered and enjoyed. Go after them with vigor. It will make you more positively positive about the complexity of life and yourself.
2. We only have a finite time on this Earth. If you are always bummed out, you're wasting a whole lot of that time and plenty of energy as well.
Look - I'm just a guy who's passing along advice I've learned over my time here on Earth that has helped me. I've had plenty of tragedies in my life and have seen lots of thing come and go, yet...I know that holding onto those things (not that I don't treasure my memories - and the people and things in them) will only bring me - and slow me - down. Moving forward can bring positive feelings and excitement. Let go and start going.
3. Laugh a lot. If you just check things out around you you'll see that there's plenty to laugh about.
Humor can cure a lot of ills. Laughing brings positive energy to you and, if you're with other people...those around you. There are few things better than a good laugh. Do it often and you'll be a more positive person for it!
4. Stop on occasion and just be. There's nothing wrong with doing nothing.
Our society is so intense with work, play (that we often feel we HAVE to do), chores, and the humdrum around us, that we often feel guilty just doing nothing! Stop that...stop that right now! Ok...that may be a little dramatic, but, hopefully, you get my point. Don't buy into the fact that you always have to be doing something. Geez...even going to yoga class has become a scheduled event - something that must be done. And that's yoga! Relax, look around, read a book, watch TV (yeah...I know, that evil box - but why not?), or just sit "out back," "out front," or inside, with a nice glass of wine, water, or whatever, and maybe even your favorite snack and chill. Ahhhh...doesn't that feel positively great?!
5. Be spontaneous. Everything doesn't have to be scheduled (see above).
That's right...you can actually do stuff that's not on your calendar. Spontaneity has become a diminishing art. Geez...perhaps picking up a sketch pad and drawing (don't judge yourself...just do it Picasso!) can really make you look at yourself differently (and in a more positive light). Or - get in your car and drive to nowhere, somewhere, or anywhere, and enjoy the trip. It can be one of those positively delightful journeys.