Whether we're talking about time, commitment, or if you're fortunate enough to have disposable income, it's about priorities. You invest in what's most important to you at the time. I know people who regularly spend in excess of £100 and eight hours on a meal or a night out; who happily splurge on shopping trips, make-up, haircuts and fake tans. When it comes to fun, or looking good, we budget, factoring in these costs to our lives. However, investing in our health usually takes a back seat until the moment that something's either gone wrong, or feels out of control. I'm not saying you have to spend money - investment isn't always just financial; it's time, effort, focus.
This isn't a sales talk. This is a reality check. If the one thing you won't spend money or time on is improving or maintaining your health, you're a dick.