It almost seems like you have to be already in a neutral mood, not too happy not too sad before you can follow the simple mindfulness meditation tips and tchniques, like paying attention to your breath, finding a comfortable seat, peaceful corner, on and on.
Well that's not much help. If I am already calm and neutral or happy, who cares. Why mediate? It has to work when all you can see is doom and gloom, bleak future and painful present. And when you sit to meditate when you're upto your navel in alligators, all your mind tries to do is solve the problems you have and protect you from the impending disaster.
But you really need to meditate when life sucks. How?
What I have found is a simple two step process works quite nicely.
One, bring the suffering in front of you instead of hiding from it and then resist trying to solve the problem right now. Say to your self, first I must calm myself now becuase then I will be better prepared to find the best solution. Do this by separating yourself from the problems you face. Instead of I am angry, anger is arising; or instead of I am jealous, jealousy is manifesting, or I am exhausted, the body is tired. And so on. Buddhists call this selfing. So try to avoid selfing, be vigilant.
Two, scan your body and find spots where the anger, worry, sadness is showing up. It is usually in the stomach, chest or neck. While breathing regulalry, keep a focus on that part of your body.
Try this. It works for me everytime. You may have to repeat this often until it becomes a habit.
Now, should you still meditate when everything is peachy? Yes, becuase that's when the body is trained how to sit and be quiet.