It is difficult to say the words "life lessons" without sounding preachy. However things I learned by gardening fall into this category fair and square. I'll try to keep it simple and hope some of this will translate in real life...
1. Living with imperfections: Don't worry about your garden being perfect. The pristine vegetable gardens you see on magazines rarely stay that way after the photo shoot. Keep the weeds down when your plants are young. You just need to play a hand at tilting the odds in their favor. If you did that, plants will be able to compete with the weeds on their own when they are bigger. Do whatever you need to create the most favorable environment for your plants so they can be more productive.
2. Taking care of problems early on: Whether it is weeds or insect, spotting the problems early on and taking actions is the best you can do. Even if the problems seem like an non-issue. If you let the problems fester, it will come to a point of no-return, and you will lose everything.
3. Letting go: At some point of the plants life, you will find yourself putting more energy into it than it is worth. This is the time to let go. Be decisive, remove the unproductive plants, replace them with something new. No sense wasting your time wondering what could've, should've, would've. This is one way to keep your garden productive. (Now this does not translate in elderly care, just sayin...)
4. Last but not least, shit happens. When it does, take whatever actions needed and move on. Just like a good doctor you can too bury your mistakes.
Always learn from your experience or others' experience. It will not only make you a better gardener, it will make you a better person.... Happy gardening!