There's no age at which humans are performing at peak on all cognitive tasks - our various cognitive functions peak at different times and past a certain age it might make more sense to view adult intelligence not through the lens of youthful general processing speed and reasoning, but through the lens of expertise, wisdom, and purpose.
Rock Star Happiness : Rock star happiness is all about getting what you want. And we think it will make us happy. Lowered Expectations : Perhaps happiness comes from lowered expectations. If you don’t expect too much, you just might not be disappointed. Peak State Happiness: Maybe happiness is performing at your peak state. There is a certain bliss to be achieved when you conquer a goal you set for yourself.
You have a window of 2-2.5 hours of peak productivity per day, usually starting a couple of hours after waking. Those are the hours when you should be working on your most cognitively demanding tasks. The big projects. The stuff that really moves the needle.
How To Be Efficient: Dan Ariely's 6 New Secrets To Managing Your Time
Take care of your health (physically and mentally) , to ensure your mind and body are ready for growth. Manage your emotions in a constructive way. Unresolved anger, resentment, fear, and contempt create tremendous barriers to personal and professional progress. Building something new is always challenging, but should rarely be painful. Realizing we are miserable or unhappy is the first step to change.
The Simple Formula to Improving Your Performance (in Anything)