Very good advices to be happier everyday, you're right in dark time we tend to forget better days are coming, we let negative thoughts lead our mood.

Then we start to do more what make us feel better short term but worse long term , exemple skip sport and drink or watch tv.

What can save us from destructive loop : Good daily routine where we do what our body and mind need to feel great as you said meditation , sport , positive thinking, communicate, discover new culture, pleasure to learn, enjoy simple things of life, make sure we sleep anought and well, eat healthy...