32:3-4 David's failure to confess his sin immediately resulted in internal grief and external weakness for him. God oppressed him severely with discipline (cf. Heb. 12:6). Consequently David felt drained of energy. Evidently this is a description of how he felt in every aspect of his being--physically, emotionally, and spiritually.
32:5 Finally David confessed his sin to God rather than refusing to admit it. Confessing involves acknowledging that what one has done violates the will of God (cf. 1 John 1:9). The Old Testament saint had the same responsibility to confess his sins to God that we do, and he also enjoyed the same promise of forgiveness we do (cf. Lev. 5:5; 16:21; 26:40). However, God punished more sins with execution under the Old Covenant than He does under the New. If the background of this psalm is David's sins against Bathsheba and Uriah, he evidently refused to acknowledge these sins for about a year after he had committed them (2 Sam. 12:13-15).