Being aware of good ideas as they appear and having some way of keeping track of them is very important. Usually we can't summon good ideas as needed, so most forms of creative work can benefit greatly from a buffer that decouples idea consumption and execution.
Jotting down ideas also works as a process of self-discovery. Giving some shape to your potential projects will help you define what kind of things you'd like to do in the future or in which direction you should steer your career or life if those ideas really matter to you.
I only started keeping track of ideas in a more systematic way in 2008. Even having started late in life as I had, by now I've already gathered hundreds of ideas of many types
(blog posts, games, mobile apps, DIY projects, web startups, insightful talks, research projects, comic strip plots). Looking at them now makes me proud for having had them for their content and diversity, specially when I rediscover some forgotten ones that still look good.
Obviously those ideas are not going to execute themselves and since some of them are really cool or will allow me to move forward in some aspects of life, I'd like to take steps to get them moving. Today they are nothing and are expecting me to get them out of that state of nothingness, or unrealized potential. After all, good ideas are a dime a dozen, and execution is all that matters.
A huge backlog of unexecuted cool ideas can also be a bit of a psychological burden because it is, after all, a list of cool things you're not doing right now as much as a list of things you'd like to do. The trick is using is as a lever or motivation to overcome inertia and avoid letting it become a trap or weight and the 'I suck because I'm not doing the ideas' mentality.
Which brings me to the next point: There's never going to be free time if you don't start making it, and nobody is going to bless you and say 'your idea is really cool and I know you have big potential even though you never showed me any concrete output, so I'll give you an authorization to execute them'. In the beginning you are the only believer, and there's only be momentum on your thing if you start it and push it for a few rounds.
