I'd say to my younger self "you really are right to bicycle to work and to dream of someday touring cross-country by bicycle."  

Also I'd reinforce that my basic life philosophy was also on target; sex, drugs, rock 'n roll, faster horses, older whiskey, younger women, and more money.

 
Oh, I'd also drop a hint to not sell the Wal-mart stock that I bought in 1976 (unfortunately I did sell it 1 year later).