“I know that nothing I can do can affect the likely factors you are likely to face, nor your attitude and aptitude when facing them, but I wanted you to realise that I am sympathetic and supportive, in the common knowledge that this will make you feel better, no matter how objectively irrational that seems, therefore I will take the time to make you feel better, because I like it when you feel better”.
Figure out what you actually mean then just say that. My suggestions are “may you succeed” or “I hope you prosper”.
“I know that nothing I can do can affect the likely factors you are likely to face, nor your attitude and aptitude when facing them, but I wanted you to realise that I am sympathetic and supportive, in the common knowledge that this will make you feel better, no matter how objectively irrational that seems, therefore I will take the time to make you feel better, because I like it when you feel better”.
How about “I am sympathetic and supportive,” then?