Failure due to aging mechanisms is an important concern for RF circuits. In-field aging results in continuous degradation of circuit performances before they cause catastrophic failures. In this regard, the lifetime of RF/analog circuits, which is defined as the point where at least one specification fails, is not just determined by aging at the device level, but also by the slack in the specifications, process variations, and the stress conditions on each of the devices. In this paper, we present a methodology for analyzing, monitoring, and mitigating performance degradation in cross-coupled LC oscillators caused by aging mechanisms in MOSFET devices. At design time, we identify reliability hot spots and concentrate our efforts on improving these components. We aim at altering degradation patterns of important performance parameters, thereby improving the lifetime of the circuit with low area and no performance impact. We use simulations based on verified aging models to evaluate the monitoring and mitigation techniques and show that the proposed methods can increase the lifetime of the devices with no impact on the initial performance.