הַמַּשְׂבִּ֣יַע בַּטּ֣וֹב עֶדְיֵ֑ךְ תִּתְחַדֵּ֖שׁ כַּנֶּ֣שֶׁר נְעוּרָֽיְכִי׃
Who satisfieth thine old age with good things; So that Thy youth is renewed like the eagle.
Read kabbalistic (mystical) interpretation of Psalms 103:5: and classical mystical sources.