The Tree of Life spoken of in Proverbs is not the Tree of Life that was in the Garden of Eden (Genesis 2.9) and that is now in the New Jerusalem (Revelation 22.2). It is symbolic of good spiritual health. If you want to be spiritually healthy just as you desire to be physically healthy get as much understanding and wisdom as you can (3.13-18).
The only way to obtain spiritual health is to pray without ceasing, read, study, memorize and meditate on Scripture daily and fellowship with the brethren as often as possible. A way you can impart spiritual health to others is by speaking kind, loving and wise words (15.4).