I have been on a ssri (lexapro) for general anxiety with limited success and xanax (alprazolam) for panic attacks, can regular exercise be just as effective ?

Possibly: There is considerable evidence of recent that regular & committed exercise may make a real difference. No one can predict the actual outcome of exercise mentally, physically, &/or spiritually. If one makes a decision to regularly exercise, a variety of benefits may occur. For example, anxiety, panic, &/or depression may decrease considerably.Or may not even be evident..