When you're considering a decently big (or indeed any) purchase or investment of time, consider these factors.
Is it removing a negative?
This is a whole article in itself; but basically, things that remove negatives have a much longer satisfaction impact than things that add a positive, which you acclimatise to very quickly. So in other words, a car that cuts your commute from 90 to 45 minutes will likely make you happy for years; whereas one that gets you there on new leather and with a better sound system will probably lose impact after three months.
Does it add a negative?
You buy that Harley; and find yourself locked into polishing chrome every weekend. You buy that Iwatch; and find that now you're getting emails in the shower. Not all good things are good things.
Does it cost time or money; or save it?
What itch am I really scratching?
Am I buying a guitar because I want a guitar; or am I trying to find a way to relax? Pause to ask why you're really doing what you're doing. There may be a better way.
Are there lasting or memorable benefits?
A safari holiday with your kids you'll probably remember for life. Flying business rather than economy to Cape Town will be great for 12 hours, and then instantly forgotten. Assess how long whatever impact occurs is likely to last.
This is about adding activities to your life. Don't just add things that are additive/useful - look for leverage in your processes. Do things that, if implemented, unlock tens of hours of free time. Look for projects that create value whilst you sleep. Look for exercises that create massive impact per minute expended, as opposed to just impact. By insisting on leverage, the construct you build will make you superhuman.