Vaccines may not be the silver bullets we hope for. Kaiser Health News reports that any future COVID-19 vaccine could be much less effective among those suffering from obesity—and their ranks include more than 100 million people in the United States.

Widespread inactivity and unhealthy nutritional habits are at the root of many of our health issues, often starting as childhood obesity. According to the former chief medical officer of the American Cancer Society, obesity is about to replace tobacco as the biggest preventable cause of cancer.

About 2 million people die each year from obesity and other chronic conditions such as heart disease, chronic obstructive pulmonary disease, diabetes, and cancer—many of which are wholly or partially preventable. This is almost 10 times the expected 2020 COVID-19 death toll in the U.S.

According to the Centers for Disease Control and Prevention, 60% of adults have a chronic disease, with 40% suffering from multiple conditions. Chronic conditions (including mental illness) now account for over 90% of U.S. healthcare costs. As chronic diseases start at ever-younger ages, including almost half of obesity and prediabetes beginning now in childhood, the lifetime health and financial damage will continue to mount. At some point, this will cost more money than the country can print.

A recent Johns Hopkins study calculated that almost half of federal spending already goes to healthcare—up from under 5% in 1960. Over that same time frame, healthcare costs have increased from 5% of GDP to almost 18%. On average, families now pay more than $5,000 per person on health, beyond employer benefits.

What the government, employers, and families don’t pay for is being passed on to future generations via the national debt. High chronic deficits threaten military spending and other national priorities, and sky-high national debt is itself becoming a growing risk to our security.

Unfortunately, it’s not just adults who suffer. Our public health crisis is being passed along, like a bad inheritance, to our children. As with our fight against tobacco, we need to start young before health habits are set and fates are sealed. Inactive children become obese teenagers, who become adults with chronic diseases. More than 80% of children with unhealthy habits become unhealthy adults.

Besides the costs and the increased susceptibility to diseases such as COVID-19, an unhealthy nation will also have problems ensuring its own national security. For years, military leaders have warned of a looming recruiting challenge: Almost one-third of youth who volunteer for service are ineligible due to obesity.

Yes, the state of our nation’s public health is ghastly. But we can’t just declare the problem unfixable and call it a day. Giving up on this big a challenge means giving up on America. As Gen. David Petraeus said when he arrived in Baghdad in 2007, “Hard is not hopeless.” Working together, this is a war we can and must win.

Forty years of unhealthy trends show that doctors and parents alone are seldom able to persuade children to stop their unhealthy behavior. They need the support of schools to help their children develop better health habits. For example, thanks in part to effective school programs, fewer than 5% of today’s high school seniors are daily smokers, down from nearly 30% in 1976.

Proven models exist to increase physical activity and healthy nutrition cost-effectively throughout K-12: with an integrated combination of wellness policy plans, community partnerships, quality physical and health education, recess, classroom activity breaks, and related evidence-based programs and practices. In just three years, one such approach in Arizona increased the percentage of fit students from 18% to 78% of all students and reduced childhood obesity across a large Title I K-12 school district, with a high lower-income Latino and Native-American population.

School accountability systems will need to focus more on the whole-child, giving school leaders an incentive to allocate school time and resources to a more balanced school day. Some systems are already moving in this direction, but we need to move much faster as physical education, health education, and recess continue to be cut back.

How do we pay for this? It is increasingly obvious that public and private health plans can benefit financially from early, school-based preventive education, especially as we move away from fee-for-service to more health-outcomes-based payment models. As a result of more aligned incentives, health leaders are stepping outside their clinical silos to address the “social determinants of health.” The health sector can invest in K-12 to help change habits and hold schools accountable, based on health cost savings' return on investment.

K-12 schools are reopening, many of them trying new teaching approaches required for COVID-19. As schools experiment in how to better serve their students’ learning needs, leaders should also ponder how they can better serve children’s needs for a healthy present—and a healthy lifetime.