Three words to help a secular accept of impermanence: Negative visualization, early retirement, and Hedonic adaptation.
Awareness of impermancence is also one of the basic pillars of Stoicism. Once you become aware of, and appreciate, impermanence you'll: find joy every day you get to spend with your children, you'll learn to appreciate your daily cup of coffee.
When you lose something, or break something, you'll have spent significant time understanding that the things was already broken or lost. Because you have internalized that the thing was going to pass away some day, you will not only have appreciated it more while you still had it, you have also spent time preparing yourself for its demise, significantly lessenning the suffering associated with the departure.
This day will end; what good have you done?
This job will end; what good did it do you?
Your life will end: what good did you do?
Your children will die one day; what good did you do them?
Amidst all this morbid speculation actually comes an amazing liberation, coupled with a new take on life: make the most of what you have, love what you have, appreciate what you once had, and live now. Live now, 'cause you're already dying.
Here's a capitalist kicker: Once you start to realize the impermanence of stuff, you also get a much more realistic picture of what it's all actually worth. Not what it costs, but what its value is. If you google financial independence you'll find two basic approaches.
- Start a company and hopefully make a boat load of money
- Learn to live well on very little money and invest your surplus.
Approach number two relies heavily on realizing the difference between price and value. Meditating on the impermanence of everything is an amazing way to gauge that difference.
You see, you become hedonically adapted to everything, and so in time your life starts to suffer from inflation. You want newer cars, bigger homes, more stuff, more everything. Internalizing the impermanence of stuff is a great way to internalize the futility of owning all that..... crap. Hedonic adaptation robs us of our appreciation of sunrises, indoor plumbing, vaccines, a warm seat, a roof over our heads, company, electricity etc.
When you start meditating on the impermanence of everything you'll start to reverse that hedonic adaptation and start to actually LOVE a simple life. This is part of the reason why those 'weird' monks and minimalists are so eerily happy with their lack of stuff, while 'the rest of us' are busy stuffing our homes.
Accept impermanence and you'll learn to love what you have, learn to release your fears when you're stuck in a bad spot (this, too, shall pass), you'll spend less money on things that you don't need in your life, you will get a better perspective on your day-to-day life, on and on.... Once you really grok it, it becomes a pillar of a good and robust life.