Life is fleeting. It can be over in a second. Relationships can be over sooner than expected. Don't put off that phonecall with your mom, kiss your loved ones goodbye in the morning - tell them that you love them. Go for that coffee that you've been promising for such a long time. Go for long walks with your person.
You don't always have to argue.
Teamwork is important.
Instead of complaining, ask how you can help.
If you had an argument, so what, cuddling is more important.
Say yes more often.
The tv isn't everything. Switch it off every now and again.
Listen more, talk less. Not just to voices, listen to the birds singing, dogs barking, be happy that you are alive. Be grateful.
Exercise. It does your body and mind so much good. If you have a body in a fairly good working condition, use it.
Don't hold grudges.
Just be happy, it is also good for your health.