Keep Track of Time Mentally
Good thinkers keep track of time, great thinkers know what time it is without having to look at a clock. Obviously, it's extremely difficult to guess the exact minute, but maintaining an awareness of the general time throughout your day can help you stay present and focused. Smart people typically operate on predetermined schedules. If you are operating according to schedule, you should theoretically be able to accurately guess what time it is.
Stay Curious
Keeping a childlike sense of wonder and intrigue will keep you going strong in life. Constantly ask yourself and the world challenging questions. Never be afraid to try something new, to fail, or to just do nothing and think for a bit.