Not be getting any younger
Definition 1 of 1
Pro Tip 1/3Time Sensitivity
The phrase highlights urgency or the need to act due to the passage of time. 
Let's have kids soon; we're not getting any younger.
Pro Tip 2/3Gentle Reminder
Used to remind someone of their age in a mild way, often to encourage action or decision. 
Think about buying a house now, since you're not getting any younger.
Pro Tip 3/3Maturity Awareness
The phrase suggests that with age comes maturity, thus hinting at acting responsibly. 
Start saving money; we're not getting any younger.