For me this year the best improvements have come from time - these have the highest returns monetary wise too as most are free. - Meditating (Headspace or Waki

For me this year the best improvements have come from time - these have the highest returns monetary wise too as most are free. - Meditating (Headspace or Waking Up App - try the 30 day trials) - Heavily exercising 3-4 times a week ($15/week gym) - $8 Gratitude Journal app - Eating clean and cooking (cheaper than eating out) In the last 10 years (I'm nearly 30) I've invested a lot in coaching, training, conferences and books - nothing has really helped even close to as much as the above. At the end of the day my increases in salary have been mainly from keeping a critical mind, not further training. A great daily practice also makes every book I read much more meaningful.