Mindlessness, or going on autopilot, can result in missing the good things in life or ignoring important information about relationships or health.
The antidote is to practice to pay more careful attention to what is going on around you as well as inside of you.
Start a meeting with 2 minutes of silence, your attention focussed on your breath. Or take a few mindful breaths before starting your exercise routine.
Bring your attention to your breath, or the feelings you encounter while washing dishes, eating a meal, walking a dog, etc.
When you move from one activity to the next, bring your focus to your breath, or focus on one of your senses.
Anytime you feel frustrated or confused, narrow your focus and return awareness to your breath.