Money exists as a tool to move your life to a better place. If you don't want to buy garbage on Amazon, don't do it, money doesn't actually burn holes in your pocket. If you enjoy the challenge of fixing the lawn mower when it breaks, then it's fine to keep doing that.

What in your life causes you stress today? You might want to think about this for a few weeks or even months. Are you unhappy with your hobbies, social life, physical fitness, etc? Identifying the points in your life that are bringing you stress, unhappiness, and discontent is how you can put unallocated money to good use.

Of course I also acknowledge that money can't fix everything, many of life's problems require significant personal effort to resolve. If your stressor is poor communication with your spouse, you can't just pay money to make you both better communicators, but I would hope having extra money in the budget would make you realize you could afford some sessions with a licensed therapist to guide you, rather than trying to go at it alone.