Meditation is not a cure to our sadness, anxiety, and stress. However, it can provide us ways to manage them well. This is more like a promise than a definite outcome.
So, what are the direct and immediate benefits from practicing regular meditation?
Concentration meditation, which is when we focus on our breath, makes us experience peace and bliss. How does it do that? Scientifically speaking, this practice shuts down our “mind wandering” default mode network in the brain - which is always scanning past and future for interesting things to think about. This shutting off of the “wandering” brings immediate relief to our cognitive workload, and allows relaxing in the present moment.
Mindfulness meditation, which is when we use our stabilized attention (gained from concentration meditation) to introspect our emotions, bodily sensations, outside sounds or other sensory material. This allows us to examine these both closely (attention), and at a distance (being aware of examining them). This makes us an appreciate beauty surrounding us, as we start noticing vivid colors, landscapes, listening to melodious bird songs, and taking time to smell and feel texture of the food.
As a self taught and read practitioner, it was useful for me to understand this distinction. I meditate ~30 mins every day in the morning. I alternate between concentration and mindful meditation.