From Longman Dictionary of Contemporary Englishfeel your agefeel your ageFEEL HOT/COLD/TIRED ETCto realize that you are not as young or active as you used to be Looking at his grandson made him really feel his age. → feel
Examples from the Corpus
feel your age• The journey was the longest he had ridden for several years and he was feeling his age.• Treat your skin to Empathy and it will never feel its age.• By not feeling my age and by having energy and vigour.• However, she was beginning to feel her age and could not face an argument until it was unavoidable.• Other times you don't feel your age at all.• Unfortunately, this is just at the time when a woman is starting to feel her age, so is especially vulnerable.• Make me feel my age, tell you the truth!• You really start to feel you age when you spend time around these kids. 