Affects of meditation come not from prolong practices rather more from quality practices. Sitting for long periods in meditation not necessarily produce result if the meditator does not know what he or she is doing. There will be benefits from this but not significant.
When a quality meditation practice is observed consistently then progress starts to take place. One easy to recognize sign is that one becomes more observant. It is the first sign of the awakening of the superconscious mind. Your awareness is soaring within going past the subconscious and into the superconscious. Your perspective changes. You start to view things from the inside out. Your powers of observation becomes stronger.
With this new found perspective you also handle life differently. You start to adopt the attitude of intelligent action and dispassionate reaction thus handling life’s circumstances wisely.