We cannot stop but smile at how adorable babies and toddlers look when they move: they may be clumsy but their little bodies can bend as if they have no bones to stop their amazing range of motion. The reason is these toddlers have a very high amount of collagen in their joints.
Contrast this with the shock of waking up one day and find yourself unable to tie your own shoes. What happened? Indeed, over time the amount of collagen has decreased resulting in wrinkled faces and 'crispy' bodies.
Women will notice how incredibly fast this can happen once they hit menopause as estrogen has a major influence on collagen synthesis. Things get worse when we don't practice stretching and don't move enough or change sitting position often enough.
So, outside taking collagen-building and joint lubricating supplements, you should start doing stretching exercises right now! Ease into doing them. There is conflicting research on when to do it, but consensus seems it is best to do it on non-training days. You might want to join a yoga class if you can't bring yourself to do them at home.