Keep calm and respond with NAD
On the other hand, being mindful will help us greatly to notice and catch our thoughts as early as possible before they gather momentum and be able to take charge rather than fall victim to our own thoughts.
Do a quick assessment of whether the thoughts are of service to you right now in this moment and in this specific situation or not. I emphasise “quick assessment” because you don’t want to overanalyse, it is usually a simple yes or no.
Then if the outcome of your quick assessment is “yes”, then direct your attention to work consciously on the issue now.
Otherwise, if the answer is “no”; which is usually the case; then simply let the thoughts be, do not try to control them. You simply direct your attention to your breath or your body, or your environment. Using your five senses helps taking you out of your thoughts and into the reality of the moment and what needs to be attended to; even if there is nothing serious or important. Maybe what is real is that you just need to rest, watch a movie, or have fun.
By trying to control or stop your thoughts you simply give them your valuable energy and they grow and gather even more energy and momentum.