It’s critical to flex your money muscles throughout your life, not just during times of boons and busts. And it’s important to understand that how we think about money can change dramatically over time. In your 30s, you may be considering buying a home, or starting a job or a family. In your 40s, you’re probably hitting your earnings peak and maybe want to start a new business or change careers, and in your 50s, retirement is just around the bend. All those milestones require a shift in how you spend and save.