I think you can… but I also think it’s a long-term “trend” in thinking that brings it about.

The old “glass half empty or half full” thing: in actuality, it’s both, and neither.  It can’t be half-empty without also being half-full.  It’s which half you choose to focus on that makes the difference.  I think that long-term, you can develop the tendency to go straight to the more positive outlook, rather than zooming right in on the negative one (which is what I do… then have to drag myself back out of it.)  It’s a process, more than a destination, and it’s not an ‘overnight’ deal.  Progress always seems to come slowly.  Old AA aphorism: “If you walked ten miles into the woods, you’re going to have to walk ten miles to get out of the woods.”  No quick fixes, but it is possible.  I’ve met people who have done it, quite a few of them.  Be persistent, and be patient with yourself.

Too… I think there’s “emotional happy,” and “outlook happy.”  One is strictly emotional, and therefore entirely beyond our control, the other is mental, and is therefore controllable… to a degree.  Influence might be a better word to use than control.  You can’t control what you feel, only what action you take or do not take based on those feelings.  You can’t really control what you think, either, beyond a certain degree.  Try meditating – – you’ll soon find out that thoughts arise whether you want them to or not; the trick is to not “attach” to those thoughts and follow them wherever they go.  No way to just turn them off.  I like the analogy of surfing: it’s a choice to either paddle like mad and “catch” that wave and let it carry you away, or to just sit quietly and let the wave roll on by.  So, emotionally happy?  Maybe, maybe not.  It’s a matter of chance and circumstances.  You *do* have some ability to choose how you will perceive any given situation, though.  Again, it’s a matter of perspective, on which half you choose to focus on.

Hope this was of some help… or at least made some sense.  🙂